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NAVAL POSTGRADUATE SCHOOL
Monterey, California
THESIS
HEAT
BUDGETS OF THE SOUTHEAST BEAUFORT SEA
FOR THE YEARS 1974 AND 1975
by
Edward Leo Tummers
September 1980
Thesis
*
Advisor: A. R.
Milne
Approved for public release; distribution unlimited.
T197476
T
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a. OOVT ACCESSION NO
4. TITLE (1*1 SuhHtlo)
Heat Budgets of the Southeast Beaufort
Sea for the Years 1974 and 1975
t. AuTHonro
Edward Leo Tummers
J2UBU
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It. SURRLEMENTARY NOTES
It. KEY WORDS (Contlntto am rawmtom «><*• II nacoooarr ana Hmmtltf my »'««» mtmmmar)
Arctic Ocean Beaufort Sea Latent Heat
Southeast Beaufort Sea Heat Fluxes
Heat Budgets Ice Cover
Mackenzie Bay Radiation
Mackenzie River Sensible Heat
Storage Heat
Wind
Thermal Structure
20. ABSTRACT (Continue an ravaraa aldm II naeaaamwy and IdamUty »T *!•«*
Comparisons were made of the heat budgets of the Southeast
3eaufort Sea for the summer of 197 4 (a severe ice year) and the
summer of 197 5 (a good ice year) . Local meteorological data and
Dceanographic measurements obtained during the Beaufort Sea Project
iuring August of both years were used to obtain estimates of the
arious heat terms.
do ,:
(Page 1)
'£", 1473
EDITION OF I NOV tS IS OBSOLETE
S/N 0103-0 14- ««0I :
UNCLASSIFIED
SECURITY CLASSIFICATION OF THIS RAOE (»nan Dmlm gntarad)
macL&asxEXED
<*cu"" cl At»iPic*y»ow o> tmi »»qc«'^— n«.« g««— «
#20 - ABSTRACT - (CONTINUED)
Results indicate that:
(1) The ma.jor heat input to the sea is from absorbed solar
radiation; (2) the overall heat contribution from the Mackenzie
River is small in comparison to that from solar radiation;
(3) the wind patterns in early spring are the major factor in
determining the heat content of the water by summer; and
(4) the wind patterns later in the spring and summer are the
major factor in determining the ice coverage.
From the distribution of heat in the study area, three
consistent features were found: (a) a warm water core in
the vicinity of 70 °N, 138 °W; (b) a core of warmer water north
of Atkinson Point associated with the early open-water area;
and (c) a core of cold water north of Richard's Island.
DD Form 1473
1 Jan 73
S/N 0102-014-6601 ^ iieu««»* cu*Mi»«e*^ioi* o* t*u »*atr***« o««« *«»•»•*<
1 Jan 73 """ o UNCLASSIFIED
N 0102-f
Approved for public release, distribution unlimited
Heat Budgets of the Southeast Beaufort Sea
for the years 1974 and 1975
by
Edward Leo Tummers
Captain, Canadian Armed Forces
BSc.j Royal Military College of Canada, 1971
Submitted in partial fulfillment of the
requirements for the degree of
MASTER OF SCIENCE IN OCEANOGRAPHY
from the
NAVAL POSTGRADUATE SCHOOL
September, 1980
ABSTRACT
Comparisons were made of the heat budgets of the Southeast
Beaufort Sea for the summer of 197 4 (a severe ice year) and
the summer of 1975 (a good ice year) . Local meteorological
data and oceanographic measurements obtained during the Beaufort
Sea Project during August of both years were used to obtain
estimates of the various heat terms.
Results indicate that:
(1) The major heat input to the sea is from absorbed solar
radiation; (2) the overall heat contribution from the Mackenzie
River is small in comparison to that from solar radiation;
(3) the wind patterns in early spring are the major factor
in determining the heat content of the water by summer; and
(4) the wind patterns later in the spring and summer are the
major factor in determining the ice coverage.
From the distribution of heat in the study area, three
consistent features were found: (a) a warm water core in
the vicinity of 70°N, 138°W; (b) a core of warmer water north
of Atkinson Point associated with the early open-water area;
and (c) a core of cold water north of Richard's Island.
TABLE OF CONTENTS
I. INTRODUCTION 22
II. DESCRIPTION OF STUDY AREA 26
A. GEOGRAPHY 26
B. TYPICAL SEQUENCE OF ICE BREAKUP 27
C. ACTUAL ENVIRONMENTAL CONDITIONS 28
1. Sequence of Ice Breakup 28
2. Wind Conditions 30
III. THE HEAT BUDGET EQUATION 32
A. DEFINITION OF TERMS 3 2
B. ASSUMPTIONS 36
1. Start Time 3 6
2. Incident Shortwave Radiation 37
3. Albedo 37
4. Cloud Amount 37
5. Sensible and Latent Heat Fluxes 37
6. Mackenzie River Discharge 38
7. Heat Content of the Water 38
8. Ice 39
a. Ice Temperature 39
b. Ice Coverage 39
c. Ice Thickness 39
d. Ice Density 4 0
e. Ice Melting and Advection 4 0
C. ATMOSPHERIC HEAT FLUX QA 41
1. Net Radiation Q* 42
a. Shortwave Radiation 43
b. Longwave Radiation 4 6
c. Summary of Net Radiation 49
2. Latent Heat Flux Q_, 50
a. Evaporation 50
b. Vapor Pressure 51
c. Latent Heat Flux 53
3. Sensible Heat Flux Q„ 55
4. Atmospheric Heat Flux Q 57
D. OCEANIC HEAT FLUX (STORAGE CHANGE) Q 58
1. Mackenzie River Heat Q 58
2. Warming Q 60
3. Melting Qp 62
4 . Advection Q_ 64
E. SUMMARY OF HEAT BUDGET EQUATION 6 5
IV. CONCLUSIONS 68
APPENDIX A: SUMMARY OF MARINE SURFACE OBSERVATIONS 70
APPENDIX B: DETERMINATION OF DAILY FLUXES IN AUGUST 71
APPENDIX C: EXTREME VALUES OF HEAT FLUXES AND
ASSOCIATED ENVIRONMENTAL CONDITIONS 76
APPENDIX D
APPENDIX E
APPENDIX F
APPENDIX G
APPENDIX H
DISTRIBUTION OF HEAT 8 2
SELECTED PROFILES AND CROSS-SECTIONS 91
SELECTED OCEANOGRAPHIC TIME-SERIES 99
COMPARISON OF SURFACE SALINITIES 100
SURFACE AIR TEMPERATURES AT BARTER
ISLAND AND CAPE PARRY 101
APPENDIX Is EXPLANATION OF MARSDEN SQUARE GRID SYSTEM 103
LIST OF REFERENCES 195
INITIAL DISTRIBUTION LIST l97
LIST OF FIGURES
Figure
1: The study area in the Southeastern Beaufort Sea 105
2: Place names in the study area 106
3: Bathymetry of the study area and a comparison of
the maximum extent of open water in each year 107
4: Map of median clearing dates - 2/10 ice or less 108
5: Mean sea level atmospheric pressure chart for May 109
6 : A time sequence showing three stages of the spring
breakup in 1975 11°
a) There was a large open-water area seaward of the
edge of the landfast ice on 21 March 197 5;
b) The offshore lead increased in width by 2 April
1975;
c) Southward advection of the polar pack reduced
the open water area by 1 May 1975.
7: Comparison of open-water area on 16 May 1974
and 13 May 1975 111
8: Comparison of open-water area on 27 May 1974
and 2 June 1975 112
9: Comparison of open-water area on 19 June 1974
and 21 June 1975 113
10: Plot of open-water area in study region of
Beaufort Sea 114
11: Wind vectors and division into wind periods for
August 1974 and 1975 115
12: Climatic feedback linkages 116
13: Typical summer fluxes in the SE Beaufort Sea 117
14: Distribution of meteorological observations for
August 1974 by Marsden sub-sub-square 118
15: Distribution of meteorological observations for
August 197 5 by Marsden sub-sub-square 119
Figure
16: Incident Solar radiation 120
17: Summary of atmospheric fluxes 121
18: Atmospheric flux QA 122
19: Accumulated heat content Q 123
20: Comparison of atmospheric fluxes Q 124
21: Summary of Oceanic fluxes 125
22: Accumulated heat content QT, Q_, Q.., Qj, QA 126
23: Mackenzie River discharge volume and temperatures
and the relationship to breakup and freeze-up
of landfast ice in Mackenzie Bay 127
24: Oceanographic stations, 1974 summer 128
25: Oceanographic stations, 197 5 summer 129
26: Heat due to ice melting in study area versus
concentration of ice 130
27 : A heat budget equation calculation comparing
accumulated heat terms from May 1 to August 15
for 1974 and 1975 131
28: Wind speeds and wind direction versus time
during August 1974 from marine observations 132
29 : Air temperatures and water temperatures versus
time during August 1974 from marine observations - 133
30: Dew point temperatures and cloud amounts versus
time during August 1974 from marine observations - 134
31: Wind speeds and wind direction versus time
during August 197 5 from marine observations 135
32: Air temperatures and water temperatures versus
time during August 1975 from marine observations - 136
33: Dew point temperatures and cloud amounts versus
time during August 1975 from marine observations - 137
34: Sensible heat flux versus time in August 1974 138
35: Latent heat flux versus time in August 1974 139
Figure
36: Latent and sensible heat fluxes over ice
versus time in August 1974 140
37: Net radiation flux versus time in August 1974 141
38: Atmospheric flux versus time in August 1974 142
39: Heat fluxes versus wind direction in August 1974 - 143
40: Sensible heat flux versus time in August 1975 144
41: Latent heat flux versus time in August 1975 145
42: Latent and sensible heat fluxes over ice versus
time in August 1975 146
43: Net radiation flux versus time in August 1975 147
44: Atmospheric flux versus time in August 1975 148
45: Heat fluxes versus wind direction in August 1975 - 149
46: Daily average atmospheric flux Q during
August 1974 and 1975 150
47 : Accumulated atmospheric heat QA during August
1974 and 1975 151
48: Current field during a northwest wind 152
49: Heat content during northwest winds, August
12-20, 1974 153
50: Mean layer temperature during northwest winds
August 12-20, 1974 154
51: Depth of the -1.5°C isotherm during northwest
winds, August 12-20, 1974 155
52: Current field following a northwest wind 156
53: Heat content during the post- northwest wind
period, August 20-23, 1974 157
54: Onshore and offshore movement of Mackenzie
River water due to wind 158
55: Current field during east winds 159
56: Heat content during east winds, August 25
to September 1, 1974 160
10
Figure
57: Depth of the -1.5C isotherm during east winds
August 25 to September 1, 1974 161
58: Mean layer temperature during east winds,
August 25 to September 1, 1974 162
59: Heat content during strong northwest winds,
August 5-13, 1975 163
60: Mean layer temperature during strong northwest
winds, August 5-13, 1975 164
61: Heat content during variable winds, August
13-19, 1975 165
62: Mean layer temperature during variable winds,
August 13-19, 1975 166
63: Heat content during light northwest winds,
August 20-24, 1975 167
64: Mean layer temperature during light northwest
winds, August 20-24, 1975 168
65: Heat content during the period August 5-24, 1975,
assuming synoptic oceanographic observations 169
66: Mean layer temperature during the period August
5-24, 1975, assuming synoptic oceanographic
observations 170
67: Depth of the -1.5°C isotherm during the period
August 5-24, 1975 assuming synoptic oceanographic
observations 171
68: Temperature contours at 5-meter depth, August 1975 - 172
69: Temperature contours at 10-meter depth, August 1975 - 173
70: Temperature contours at 15-meter depth, August 1975 - 174
71: Temperature contours at 20-meter depth, August 1975 - 175
72: Salinity, density and temperature versus depth at
Station 12, August 18, 1974, and Station 13,
August 14, 1975 176
73: Location of oceanographic vertical cross-sections
A, B, and C in the study area during August 1974 177
74: Temperature and density cross-section A 178
11
Figure
75: Temperature and density cross-section B. A cold
water intrusion is outlined by the -1.5°C
isotherm 179
76: Temperature and density cross-section C. Shown
are two tongues of warm water at the surface and
a cold intrusion riding up the continental shelf — 18 0
77: Location of oceanographic vertical cross-sections
D, E, F, G, H, I, J, Kin the study area during
August 1975 181
78: Temperature and density cross-section D. A wedge
of warm water at the surface decreases in depth
with the distance seaward, and cold water is
seen along the continental slope at a depth of
about 25 meters 182
79: Temperature and density cross-section E. A wedge
of warm water decreases in thickness with the
distance seaward 183
80: Temperature and density cross-section F. An
intrusion of cold water rises inshore to a depth
of 15 meters along the continental slope 184
81: Temperature and density cross-section G. An
intrusion of cold water is seen along the con-
tinental slope to a depth of about 18 meters.
Also shown is an upwelling of the cold water north
of Richard's Island indicated by the decreasing
water surface temperatures between Station 39
and the shore 185
82: Temperature and density cross-section H. There
was a warm wedge which thinned as the distance
seaward increased 186
83: Temperature and density cross-section I. There
was a well-mixed layer of 5°C water to a depth
of 15 meters between Stations 27 and 29 and a
core of warmer 3°C water at 20 meters below
Station 27 I87
84: Temperature and density cross-section J. This
shows the complex temperature structure north of
Tuktoyaktuk Peninsula in the vicinity of the area
where the first open water appeared beyond the
landfast ice early in the season. Station 5 was
occupied almost two weeks before Station 32 and it
12
Figure
84: (Cont.)
is seen that cooling occurred during northwest winds
and there was subsequent heating of the upper 10
to 15 meter thick layer 1°°
85: Temperature and density cross-section K. There
was a relatively simple temperature structure
with a decreasing thickness of a warm wedge as
the distance seaward increased 189
86: Hourly time series at Station 11 in Mackenzie Bay,
August 15-18, 1974 i9°
87: Hourly time series at Stations 19 and 48, north of
Tuktoyaktuk, August 23-24, 1975 191
88: Comparison of surface salinities: summers of
1974 and 1975 192
89: Comparison of surface air temperatures at Barter
Island and Cape Parry based on 5-day mean tempera-
tures in 1974 and 1975 from June 20 to October 10
of each year 193
90: The study area showing the Marsden sub-sub- square
grid 194
13
LIST OF TABLES
Table
1: Typical values of albedoes over various surfaces 47
2: Relationship of Q_ and corresponding area of
ice advected 66
3: Extreme values of upward heat fluxes and
associated environmental conditions over
water only 77
Extreme values of upward fluxes and associated
environmental conditions over the entire study area -
78
5: Extreme values of downward heat fluxes and
associated environmental conditions over water only - ^0
6: Extreme values of downward fluxes and associated
environmental conditions over the entire study area - 81
14
SYMBOLS AND ABBREVIATIONS
Conversion Factors, Constants, and Notation
The following list of conversion factors, constants, and
notation represents those most frequently used during the
preparation of this paper and may be helpful in comparing
results found elsewhere expressed in different units or
using different notations.
-5 -1 -2 -4
Stefan-Boltzman constant - 5.735x10 erg sec cm °K
= 1.18 x io~7 ly day~loK"4
1 watt m~2 - 753 ly year"1 = 2.063 ly day"1
1 gm cal - 4.183 joules
3
1 m sec - 35.31 cfs
1 m2 - 10.76 ft2
1 km2 - 0.3861 (statute miles)2
= 0.2913 (naut. miles)
1 km - .5397 nm
1 knot - .514 m sec
At 70 °N, 1 degree latitude- - 111.6 km
1 degree longitude - - 38.75 km
2
1 degree square - ~ 4326 km
A - Albedo
C - Cloud amount (tenths)
CONC - Concentration of ice (tenths)
E - Evaporation rate (cm day )
15
e - vapor pressure (mb)
e_ - vapor pressure of the air (mb)
a
e - vapor pressure of the surface (mb)
K - coefficient indicating surface roughness
K' - coefficient indicating atmospheric stability
K+ - incident shortwave radiation at the surface of the
earth (ly day"" )
Kt - reflected short wave radiation (ly day )
L - Latent heat (cal gm )
L - Latent heat of sublimation (taken as 677.0 cal gm )
L - Latent heat of vaporization (taken as 597.3 cal gm )
L+ - the incident long wave radiation at the earth's surface
(ly day"1)
Lt - the reflected long wave radiation (ly day )
M - the molecular weight of water vapor = 0.622 Molecular
weight of dry air
-3
p - the density (gm cm )
Q, - Resultant atmospheric flux (ly day )
QA - Accumulated atmospheric heat (ly)
QE - Latent heat flux at the surface (ly day )
QE - Accumulated latent heat at the surface (ly)
QF - Heat flux due to the cooling or warming of the ice and
subsequent freezing or melting (ly day~l)
Q„ - Accumulated heat used in warming and melting the
ice in place (ly)
Q - Sensible heat flux at the surface (ly day" )
Q„ - Accumulated sensible heat (ly)
Q - Heat flux due to advection of ice (ly day" )
QT - Accumulated heat due to ice advection (ly)
16
Qs - The storage change in the water column (ly day )
Q_ - Accumulated storage heat due to oceanic fluxes (ly)
QT - The heat transported by Mackenzie River water (ly day )
Q^, - Accumulated Mackenzie River heat (ly)
The heat due to the cooling or warming of water in
the upper layer of the ocean (ly day"1)
Q
Qw - Accumulated heat used in warming the upper layers
of the ocean (ly)
Q* - The net radiation flux of downward and upward solar,
terrestrial, and atmospheric radiation (ly day~l)
Q* - Accumulated heat due to net radiation
R* - The universal gas constant (M /R* = 9.08 gm cal~ °K)
for dry air
T - Temperature (°C or °K as specified)
T - Air temperature
T, - Dew point temperature
T. - Ice surface temperature
T - Water surface temperature or ice surface temperature
as applicable
T - Water surface temperature
V - Wind speed (m sec )
e - Stef an-Boltzman constant
a - Emissivity of the surface
17
Summary of Equations*
1. Q* + QE + QH + QT + Qw + Qp + Qj = 0 32
2. QA = Q* + QE + QR 34
3. Qs = QT + Qw + QF + Qz 34
4. QA + Qs = 0 34
5. Q* + QE + QH + QT + Qw + QF + Qj = 0 34
6- QA + Qs ■ ° 35
7. Q* = K+ + Kt + L + + Lt 43
8. K+ + K+ = K+(l-A) 43
9. L+ + Lt = ecT4(l - 0.44 - 0.08/e) (1 - 0.083C) 46
10. E = KV(e - e )
w a
12. QE = p LE
13. Q_ + Q_(ice) (CONC) + Q_( water ) (1 - CONC)
El El h
*
page numbers refer to first reference to equation
50
ML, , .
11. e - 6.11 EXPC-^rC^y - f] 51
53
54
14. Q„ = 30.24(T -T) 55
a s a
15. Qu = 0.42 V (T -T ) 56
ri s a
18
16. Qs = QT + Qw + QF + Qz 58
17. Q = Q(ice) (CONC) + Q (water) (1 - CONC) 72
19
ACKNOWLEDGMENT
The topic for this thesis was suggested by Adjunct
Research Professor of Oceanography Allen R. Milne, Chair
in Arctic Marine Sciences of the Naval Postgraduate School,
Monterey, California. His invaluable experience in the
Arctic and especially the Southeast Beaufort Sea, and his
interest and guidance in directing the research efforts were
an inspiration and contributed immensely to the successful
completion of this research. Professor Robert G. Paquette,
also of the Naval Postgraduate School provided helpful back-
ground ideas based on his own extensive experiences in the
Arctic. The support and cooperation of the faculty and staff
of the Naval Postgraduate School helped make the research
enjoyable. The patient understanding of my wife, Sandra, and
my son, Patrick, during the long hours of research was greatly
appreciated. To these people, the author expresses his sin-
cere thanks .
20
"If you want to know what men look for in that
land (the Arctic) or why men go where there is such
danger to their lives, it is the threefold nature of
man that lures him on. One part of man wants fame,
for man goes where there is great danger to make
himself famous. Another part of man wants knowledge,
wants to see those places he has heard of and find
out if they are as he has been told. The third part
is the desire for riches, for man pursues wealth
wherever he thinks he can find it, even though he
must pass through great dangers."
Unknown bard
from The Mirror of the King
(a thirteenth century
Viking ballad)
From The Northwest Passage, by Bern Keating, Rand McNally
& Co., Chicago, New York, San Francisco, 1970, p. 9.
21
I. INTRODUCTION
The primary aim of this study was to compare the heat
budgets during the summer open-water season of 1974 (a severe
ice year) and of 197 5 (a good ice year) in the Southeast Beau-
fort Sea study area (Figure 1) . The heat fluxes during each
period were estimated in order to obtain values for accumulated
heat due to these fluxes for the period May 1 to August 15.
Mid-August was chosen for the heat budget calculation because
simultaneous meteorological and oceanographic observations in
the study area were available for each year with which to
calculate the individual terms of the heat budget equation
(Section III) .
The atmospheric flux QA was estimated for the early part
of the season and calculated for August of each year when
marine meteorological observations were available (Section
III.C). Walmsley (1966) conducted a similar study in Baffin
Bay for the period 1919-1942 and Huyer and Barber (1970) calcu-
lated a heat budget for Barrow Strait in 1962. Both authors
reported a maximum Q, flux downward in July with a rapid decrease
in August which was also evident in the study area (Section
III.C.) .
It was desired to take some steps to develop a basic
understanding of the heat budget and the associated oceanography
in the Southeastern Beaufort Sea, an area of increasing commer-
cial importance. The problem differs from those of Walmsley
22
(1966) and Huyer and Barber (1970) in two ways in particular.
In their cases, the advection of ice was reasonably predic-
table because the areas were relatively well-bounded. Also
the present area of study includes the drainage from a major
river, the Mackenzie, which tends to cause ice to melt earlier
and thus increases the absorption of heat due to solar radia-
tion.
The techniques of the present study are somewhat similar
to those of the previous authors except that now a considerable
number of oceanographic observations were available. These
made it possible to calculate the storage heat and permit a
comparison of the atmospheric terms and the oceanic terms with
a resultant estimation of the advection of ice. The details
of the calculations are described in Section III.
It was found that:
(1) the major heat input to the Southeast Beaufort Sea
was from absorbed net radiation Q* , regardless of the severity
of the ice cover;
(2) the overall heat contribution from the Mackenzie River
Q_, varied little inter-annually and was small in comparison
to the contribution from net radiation Q*;
(3) wind patterns in early spring were the major factor
in determining the heat content of the water in summer and
the severity of the ice early in the navigation season; and
(4) wind patterns later in the summer were the major
factor in determining ice coverage. Onshore winds produced
23
severe ice conditions, whereas, offshore winds produced good
ice conditions.
A summary of marine meteorological observations for air
temperature, sea surface temperature, dew point temperature,
cloud amount, wind speed and wind direction is presented in
Appendix A. The results of the calculations of the individual
atmospheric flux terms corresponding to the marine observations
are presented in Appendix B. The extreme values of the atmos-
pheric fluxes and the associated environmental conditions were
examined in more detail in Appendix C. It was found that on-
shore winds (from 260° to 350°) produced maximum heat losses
(upward fluxes) . Conversely, offshore winds (from 090° to
190°) produced maximum heat gain (downward fluxes) .
In addition, various data presentations having oceanographic
interest have been made. The distribution of heat in the water
column of the study area was determined from examination of the
temperature profiles at each oceanographic station. The results
are displayed and discussed in Appendix D. Based on the dis-
tribution of heat throughout the study area, selected tempera-
ture and density profiles and cross-sections were examined in
more detail to highlight interesting features in the circulation
pattern (Appendix E) . It was found that
(1) the heat content of the water column Qw, was much higher
in 197 5, a good ice year, than in 197 4, a severe ice year;
(2) a warm water core in the vicinity of 70 °N, 138 °W existed
in both years and with a similar heat content;
24
(3) a core of warmer water north of Atkinson Point, apparently
associated with the transient patch of open water which has
come to be called the Bathurst Polynya, was evident in both
years ; and
(4) in August 197 5, a core of cold water just north of
Richard's Island indicated that upwelling occurred and that
there was in-shore movement of cold Arctic surface water on
the shelf from beyond the continental slope.
A detailed examination of the study area, the environmental
conditions in each year of the study period, and the evaluation
of each term of the heat budget equation follows.
25
II. DESCRIPTION OF THE STUDY AREA
A. GEOGRAPHY
The study area (Figure 2) extends in an east-west direc-
tion from Herschel Island at about 14 0°W to Cape Dalhousie at
128 °W, and in a north-south direction from the shores of the
Mackenzie Delta and Tuktoyaktuk Peninsula to as far north as
oceanographic observations were available. Figure 3 shows the
region's bathymetry and the northerly limits of pack ice in
the study area for the summer of years 1974 and 1975. The
Mackenzie Canyon (also known as Herschel Canyon) is seen to
extend southward into Mackenzie Bay east of Herschel Island
and toward the western outlet of the Mackenzie River in Shallow
Bay. Along Richard's Island the Tuktoyaktuk Peninsula, the
continental shelf extends seaward to a distance of 110-150 km.
In the Mackenzie Bay region, the nearshore water is very shallow
with the ten-meter isobath lying as far as 35 km offshore. Only
ice scours and underwater pingoes mar the flatness of the con-
tinental shelf. There is a smaller canyon on the shelf just
north of Richard's Island (noticeable in the 50-meter contour
in Figure 3) extending southward towards Kugmallit Bay and the
eastern outlet of the Mackenzie River. At the northern limit
of the study area at the shelf break the slope drops quickly
to depths over 1000 meters.
26
B. TYPICAL SEQUENCE OF ICE BREAKUP
Nearshore, ice breakup usually starts in the Delta region
(Figure 4) one week after the mean air temperature exceeds
0°C on about June 18 and is caused by rising air temperatures,
warm water input from the Mackenzie River, and the melting of
the snow cover. These factors are in turn controlled by the
solar radiation, air temperature, precipitation, wind, cloudi-
ness, vapor pressure, and evaporation. The relatively warm
water of the Mackenzie River at its peak freshet in mid-June
hastens the breakup of ice in the vicinity of the Delta [Burns,
1973] . The breakup of ice begins in Shallow Bay, then Kugmallit
Bay and then progresses along the coast in both directions.
The ice may be expected to loosen and break up early in July
and, except in a severe ice year, a wide expanse of open water
exists along the coast throughout August and September. In
severe ice years, like 197 4, open water may not occur until
well into August and ice may reform in September. The expanse
of open water in summer depends largely on winds, which can
vary considerably in their prevailing direction from year to
year. Cold winds from the northwest sector blow onshore pressing
the Beaufort Sea pack ice landward, and if they prevail through-
out much of the summer, it will be a severe ice year. On the
other hand, warm easterly and southerly winds blowing offshore
in summer move the pack ice away from land and with melting
open a passage from Point Barrow to Cape Bathurst.
Offshore, beyond the landfast ice, the development of
flaw leads and polynyas occurs mostly in April and May when
27
the offshore wind patterns change to a southeasterly flow and
refreezing is slower as air temperatures begin to rise [Markham,
1975].. The long-term mean surface pressure chart for May
(Figure 5) illustrates the development of these offshore winds.
The High over the Chukchi Sea in February moves eastward and
combines with the trough developing in Central Alaska to give
southeast winds in the Beaufort Sea. Polynya and lead forma-
tion seaward of the landfast ice follows quickly. The regions
north of Cape Bathurst in the eastern part of the study area
(Figure 4) become the centers for offshore disintegration of
ice, allowing the penetration of solar energy into the water,
furthering the breakup process by accelerating melting. The
offshore breakup in the Southeast Beaufort Sea is highly depen-
dent on a change in the wind regime, on increasing solar radia-
tion, and to a lesser extent on the tides and oceanic circulation
C. ACTUAL ENVIRONMENTAL CONDITIONS
1 . Sequence of Ice Breakup
The sequence of ice breakup in the spring and summer
of the study period is described below. In 1974, there was
no open water until mid-May. Figure 6 shows a sequence of
satellite photos taken in 197 5 on March 21, April 2, and May
1 showing the development of the leads at the edge of the fast
ice. The lead was almost entirely closed again by May 1 due
to a shift in winds. The next series of figures (Figures 1 ,
8, 9) show the contrast in open water at the same time of year
between 1974, a severe ice year, and 1975, a good ice year.
28
The summer of 197 4 was characterized by the worst ice
conditions for 20 years of records in the Southeast Beaufort
Sea. In contrast, sea ice gave little trouble to shipping
in the study area in 1975. Figure 7 shows satellite photos
for mid-May of each year. The large expanse of open water
north of Cape Bathurst has re-appeared in the 1975 imagery,
whereas there is little open water in mid-May 1974. Figure 8
shows satellite imagery for the beginning of June of each year.
The open-water area north of Cape Bathurst has continued to
spread in 197 5, whereas in 1974 there was virtually no open
water. Figure 9 contrasts ice conditions at approximately 21
June, the summer solstice. In 1975, except for a fringe of
landfast ice, the entire area is ice-free; whereas in 1974,
there is still almost total ice cover. Visible satellite
imagery for the remainder of each summer is poor due to cloud
cover; infra-red satellite imagery is poor due to the small
temperature differences between open water and the ice cover.
Figure 10 plots the percentage of open-water area from May 1
to the end of September for each year.
From the middle to the end of July 1974, the limit of
open water remained near the ten-meter depth contour.. By
mid-August, the limit had moved outward in an expanding arc
from Herschel Island to 70°N and then eastward to Atkinson
Point. By August 19, the ice had returned onshore at some
places in between. North of the limit of open water there
existed large areas of first-year ice in various states of
decay. These ice conditions coincided with a lack of persistent
29
winds from the east and south which usually blow in summer
forcing the ice offshore. The north-to-west winds held the
ice onshore and made synoptic oceanographic observations of
the study area impossible. Marine observations were limited
to a narrow band of open water along the coast between Herschel
Island and Atkinson Point. The resulting heat budget calcu-
lations were considered to be representative of a heavy-ice
year.
2. Wind Conditions
The data collected during August of 197 4 was sparse
both in time and space. Because of rapidly changing condi-
tions in the study area, it was not valid to assume that the
oceanographic data was synoptic. As an alternative approach,
the open-water study period in August was examined by consider-
ing three evident prevailing-wind conditions in the wind records
included in the marine surface observations (Appendix A) . By
examining these three shorter time intervals, the assumption
of synopticity is made more reasonable even though the number
of observations in each wind period is reduced. The observa-
tion period from August 12 to September 1 was divided as
follows (Figure 11);
August 12-20, 1974 Prevailing northwest winds
August 20-23, 1974 Light and variable winds
(called the post-northwest
winds)
August 24-31, 1974 Easterly winds
(encompassing 010° to 180°)
In the summer of 1975, on the other hand, the main
pack ice stayed north of 71 °N throughout most of the study
30
area, and remained at about 70 °N near Herschel Island. Thus
the two research ships were able to work out to the edge of
the continental shelf. Later in August 197 5, westerly storms
did bring ice further south, but in low concentrations which
was less troublesome than the polar pack for navigation. The
large expanse of open water resulted in deeper wind-mixing
of the upper layer of the ocean in the summer of 1975. The
long fetch and absence of ice allowed wind-waves to build
and produced turbulent mixing of the upper layer. The dominant
winds for August 197 5 are shown in Figure 11.
August 5-12, 1975 prevailing northwest winds
August 12-16, 1975 southeast winds
August 16-20, 1975 northeast winds
August 21-24, 1975 northwest winds
In 197 5 the large expanse of open water occupied by
a relatively small number of oceanographic stations between
August 5-24 did not permit the separation of data into shorter
time intervals identified with the particular wind direction.
Instead, a synoptic evaluation of the heat budget for the entire
observation period August 5-24 was made, in contrast to the
approach used in August 1974.
31
III. THE HEAT BUDGET EQUATION
Energy fluxes over Arctic Seas comprise a complicated
interaction of a variety of energy mechanisms and feedback
loops (Figure 12) , which will be discussed in succeeding
sections .
A. DEFINITION OF TERMS
Figure 13 shows the typical summer fluxes in the South-
eastern Beaufort Sea. The energy gained by the system is
denoted by negative fluxes. The energy lost by the system
to its surroundings is denoted by positive fluxes. The
resultant energy stored in the system is denoted by a positive
sign if it is an increase in stored energy, or by a negative
sign if it is a decrease in stored energy. All fluxes ('Q1
terms) are expressed in units of "calories per square centimeter
-2 -1
per day" (cal cm ' day ) or equivalently as langleys per day
(ly day ) . The accumulated heat due to each flux, expressed
as the time integral of the flux term, is written as a Q term,
which includes all heat within the entire study area (46,794
2
km ) attributable to the associated flux term. The units of
the accumulated heat (Q) terms are "gram-calories" (g cal) .
The fluxes shown in Figure 13 may be summed to give the heat
flux equation:
Q* + QE + QH + QT + Qw + QF + Qj = 0 (1)
32
y
where: Q* (-) is the net radiation flux of downward and
upward solar, terrestrial, and atmospheric radiation (the
negative sign indicates that the net radiation is directed
downward and results in a net gain of heat by the system) ;
Q_(+) is the heat loss by the system due to the latent
E
heat flux between the surface and the atmosphere (a positive
sign indicates that a heat loss is due to evaporation; a
negative sign would indicate that a heat gain was due to
condensation) ;
Q„(+) is the upward transfer of sensible heat from
n
the surface to the atmosphere and represents a heat loss by
the system;
Q (-) is the heat input due to the Mackenzie River
freshet and represents a heat gain by the system;
Qw(+) is the heat used to warm the water in the upper
layer of the ocean (a negative sign indicates that heat was
released to the system from cooling of the water column) ;
Q_,( + ) is the heat used to warm the ice and subsequently
melt it in place (a negative sign would indicate that freezing
and cooling of the ice had occurred) ; and
QT(+) is the heat used to melt imported ice (a nega-
tive sign would indicate that ice had been exported and that
heat which would have been required to melt the ice is now
available in the system as a gain of heat) . Q is essentially
the difference between the atmospheric heat Q and the sum
of QT, Qw and Q which in the absence of ice advection and
errors in the other terms, would be zero.
33
Equation (1) may be simplified by grouping of the fluxes
as atmospheric and oceanic. Thus
QA - Q* + QE + QH (2)
where Q (-) is the resultant atmospheric flux downward; and
Q^ = Qm + QTT + Q^ + Qt (3)
VS T W F I
where Q_ (+) is the resultant oceanic flux or storage change
in the water column and ice cover. The positive sign indi-
cates that there has been an increase in stored energy in the
water column and ice cover (as would be expected in the Arctic
summer) . A negative sign would indicate that there had been
a decrease of stored energy (as would be expected in the
Arctic winter) .
The heat flux Equation (1) may now be written in simplified
form by combining Equations (2) and (3) such that:
QA + Qs = 0 (4)
Each flux term ('Q') is associated with an accumulated
heat term ('Q'). Therefore by writing Equation (1) in terms
of accumulated heat, the expression for the heat budget equa-
tion (Equation (5)) is derived:
Q* + QE + QH + QT + Qw + QF + Q = 0 (5)
34
where each term represents the accumulated heat or time
integral of the related flux.
Q* is the accumulated heat due to the net radiation;
Q_ is the accumulated latent heat;
QH is the accumulated sensible heat;
QT is the accumulated Mackenzie River heat;
Qw is the accumulated heat used in warming the
upper layers of the ocean;
Q_ is the accumulated heat used in warming and
melting the ice in place (and is directly
related to the ice coverage) ; and
QT is the accumulated heat due to ice advection.
Just as was done for the fluxes, Equation (5) may be
simplified to
QA + Qs = 0 (6)
where Q (-) is the accumulated heat due to the atmospheric
fluxes representing a gain of heat by the system; and
Qs (+) is the accumulated storage heat due to oceanic
fluxes and represents the increase of stored energy in the
water column and the ice cover. In words. Equation (6) says
that the net heat gained by the system (Q,) is stored as
energy in the system (Q ) .
35
B. ASSUMPTIONS
The heat budget calculation is limited in its accuracy
because it was not possible to obtain all the data required
for a complete calculation of each term. The balance is also
limited by uncertainties in each term which are discussed later
in Section III. The following assumptions were made in the
determination of the heat budget.
1. Start Time
It was assumed that the accumulation of heat began on
May 1 of each study year, that being the approximate date
that the ice breakup begins offshore of the landfast ice
according to climatology [Markham, 197 5] . The accumulated
heat terms, Q, are all zero on May 1. This amounts to assuming
that all water columns are isothermal at -1.5°C, the refer-
ence temperature for the heat calculations . This is a reason-
able assumption in view of Spring observations reported by
Herlinveaux, de Lange Boom and Wilton (1976) which support
the idea of an isothermal water column containing no heat
relative to the reference temperature. The satellite photos
for the early spring of 1975 (Figure 6) show that the open-
water area in late March and early April was almost completely
ice-covered again by May 1. Any heat that was absorbed by
the open water during the period before May 1 can be safely
assumed to have been extracted by the advection of ice into
the region in the last week of April. The Mackenzie River
input does not begin until mid-May after thawing begins [Davies,
1975] .
36
2. Incident Shortwave Radiation
Incident shortwave radiation fluxes over the study
area were assumed to be the same as those measured at Sachs
Harbor [Department of the Environment (Canada) Radiation
Summary, 1974 and 1975] until the time that the marine
observations became available. Then values of incident solar
radiation fluxes were used as discussed in Section Ill.C.l.a.
3. Albedo
The ice albedo was taken to be 8 0% until the end of
May and then diminished stepwise linearly to 30% in July as
puddling occurred at the height of the ice melt. Later for
August the ice albedo was a slightly greater 40% corresponding
to melting but drained ice. Over open water an albedo of
7% was used (see Table 1, Section III.C.l) [Orvig, 1970 and
Sellers, 1965] . The effective albedo over the study area was
calculated using the ice concentration, ice albedo, and open
water albedo .
4 . Cloud Amounts
The cloud amounts for the period from May 1 to the
start of marine observations were the climatological averages
reported by Burns (1974) . During the period of marine obser-
vations in August, the cloud cover was assumed to be the
same throughout the study area as that reported at the actual
location.
5. Sensible and Latent Heat Fluxes
Sensible and latent heat fluxes over ice and water
were based on climatology [Burns, 1973] for the period from
37
May 1 to the start of marine observations after which they
were calculated based on actual observed parameters existing
in the study area.
6 . Mackenzie River Discharge
No discharge volumes were available for 1975. Be-
cause there is little inter-annual variation in discharge
volumetric rates [Herlinveaux, 1976] it was assumed that the
discharge rates for 1972 (a similarly good ice year) could
be applied to 1975 (see Section III.D.l). This was assumed
to be the only current advecting heat through the boundaries
of the study area. The surface currents within the area vary
considerably, but residual currents appear to be weak and
would therefore cause little heat change by advection when
compared to the river's heat input during the summer.
7 . Heat Content of the Water
Temperature measurements were never taken right to
the bottom so that the heat content below the deepest water
temperature measurements was unknown. As such, it was assumed
to be zero. When water temperatures were below -1.5°C (the
reference temperature) , there was little error, but in shallow
water where temperatures often remained high right to the
bottom, the calculated heat content will be less than the
actual heat content of the water. This error will result in
a consistent underestimate of QTT. The heat content below an
ice surface was assumed to be zero.
38
8. Ice
a. Ice Temperature
It was assumed that the ice temperature was -7°C
on May 1, that it warmed to 0°C throughout the entire thick-
ness by May 15 and that it remained at 0°C for the duration of
the summer, until freezing began again in September. Vapor
pressures over ice were calculated based on a surface tempera-
ture of 0°C. There is some argument for assuming that ice
surface temperatures can rise above 0°C due to warming of the
melt water [Vowinckel and Orvig, 1964] which could result in
small errors in the calculation of back radiation and smaller
errors in the calculation of the latent and sensible heat
fluxes over ice. It was further assumed that no heat was
stored in the ice.
b. Ice Coverage
Ice coverage was determined from semi-monthly
satellite photos for May and June and from weekly historical
ice charts provided by the Atmospheric Environment Service
of the Department of the Environment (Canada) for the period
in which they were available. The ice coverage was assumed
to be accurate to within 10%, and constant between successive
records.
c. Ice Thickness
The ice was assumed to be a uniform layer two
meters thick.
39
d. Ice Density
-3
The density of sea ice was taken as 0.92 gm cm
with an initial salinity of 4%.
e. Ice Melting and Advection
These terms, Q_ and Q , and the related accumulated
r I
heat terms Q„ and Q , are discussed in greater detail in
Section III.D. It should be pointed out here, though, that
there is considerable overlap in the expression of the energy
devoted to each of these terms in the equation. The following
assumptions were made:
(1) Any decrease in ice coverage was due to the melting
of ice in place and resulted in an increase in Q_, the heat
£
used to melt the ice (Q„ is a positive flux since it represents
heat lost by the system to melt ice in place) ;
(2) Any increase in ice coverage was due to the freezing
of ice in place and resulted in a decrease of Q„, the heat
released to the system by the freezing of the ice (Q„ is a
negative flux since it represents a heat gain by the system) .
It will be seen that there is considerable artificiality in
these two assumptions with regard to melting and almost com-
plete artificiality with regard to freezing, since freezing
during this period is actually slight. This arbitrary tech-
nique was followed as a convenience since it was impossible
to know the real situation. Errors produced here are reflected
reciprocally in the Q term.
(3) Ice advection Q is used to account for the balance of
heat remaining in the equation. It is obtained as a direct
40
result of balancing the heat budget equation, not from any
estimate of the physical processes. If Q is a positive
flux, it represents a volume of ice being imported, since that
represents a heat loss to the system in that the entire volume
of imported ice must be melted so that the ice coverage does
not change. If Q is a negative flux, it represents a
volume of ice being exported, since that represents a heat
gain to the system such that the volume of ice exported does
not require heat from the system to melt the ice to obtain
the ice coverage observed .
The values obtained for Q were then compared with
the direction of ice advection expected from the observed
winds. Offshore winds should result in ice export; onshore
winds should result in ice import. Because the direction of
the Q flux term corresponded to the prevailing winds, it was
assumed to be representative of what had actually happened
in the study area. The term Q represents the accumulated
effects of advection during the entire period of the heat
budget calculation.
C. ATMOSPHERIC HEAT FLUX QA
The calculation of atmospheric fluxes was based on
meteorological data provided on magnetic tape from the his-
torical files of the National Weather Records Center at Ashe-
ville, North Carolina. These records are filed by 10° Marsden
Square, year, and month and comprise all known observations.
Figure 14 shows the distribution of the 33 observations used
41
in the month of August 1974. The marine observations were
confined to the narrow band of open water near the coast.
Figure 15 shows the distribution of 159 observations used in
the month of August 1975. These observations were more evenly
distributed throughout the open-water area, but heavily weighted
by the 39 observations in Marsden sub-square 9 82 east of
Herschel Island. Each marine observation was taken to be
representative of conditions over the entire study area at that
time. In a few cases, simultaneous observations taken in
different places were averaged and applied to the entire study
area. About one-third of the observations in both years were
either incomplete or inaccurately recorded and were therefore
not suitable for use in the calculation of the atmospheric
fluxes.
No marine observations existed before the beginning of
August in each year. For these months, climatological data
were used [Burns, 1973] to determine the atmospheric fluxes
from May 1 to the beginning of the marine observations.
1. Net Radiation Q*
Q* is the net radiation flux of downward and upward
solar, terrestrial, and atmospheric radiation. It has two
components, shortwave radiation and longwave radiation, each
of which has both an upward and a downward element [Walker,
1975] . Thus Q* may be expressed by Equation (7) :
See Appendix I for explanation of the Marsden Square
grid system used.
42
Q* = K+ + Kt + LI + Lt (7)
where
IU is the incident shortwave radiation (a negative
sign because it is directed downward and represents a heat
gain to the system) ;
Kt is the reflected shortwave radiation (a positive
sign because it is directed upward and represents a heat loss
to the system) ;
L+ is the incident longwave radiation (also called
downward infra-red, a negative sign because it is directed
downward and represents a heat gain to the system) ; and
Lt is the back radiation or upward infra-red radiation
(a positive sign because it represents a heat loss to the
system) .
These terms are discussed more fully in the following
sections .
a. Shortwave Radiation (Ki + Kt)
The net shortwave radiation depends on the inci-
dent shortwave radiation and the surface albedo such that
Ki + Kt = K* (1 - A) (8)
where A is the albedo of the surface and represents the frac-
tion of the incident shortwave energy which is reflected.
The incident shortwave radiation K4- depends on
several factors including the altitude of the sun, the duration
43
of daylight, the composition of the atmosphere, the cloud
cover and the cloud type. Of these, the altitude of the sun
and the duration of daylight are accurately known for any
given position. The composition of the atmosphere varies
according to the general circulation of the atmosphere and
related synoptic systems combined with such local effects
as the presence of open water and sources of local pollution.
This factor was not considered directly. The cloud cover over
the entire study area was assumed to be that recorded in the
marine observations. The cloud type was generally unknown and
was not considered.
Incident radiation values were available from
monthly summaries of hourly radiation for Sachs Harbor and
Inuvik, both near the rim of the study area. The daily totals
of incident solar radiation Ki were plotted for each site and
compared (Figure 16) . The maximum downward values of radiation
from both years were assumed to define a curve of maximum
clear-sky radiation in the study area.
Laevastu (1960) predicts somewhat higher values
in the early part of the period and lower values in the later
part. The actual curve used was a compromise between the
observed and the predicted values. This curve is shown in
Figure 16. The daily values from this curve were then multi-
plied by a factor (1 - fraction of cloud cover) using a curve
based on cloud amounts from ship observations in the study
area (Figures 30 and 33 of Appendix A) to obtain the calculated
44
incident solar radiation (Figure 16). In each case, it was
assumed that the ship observations were representative of
the entire study area. When no ship observations were avail-
able (as in the period from May 1 to the beginning of August)
the radiation values at Sachs Harbor were taken as represen-
tative of the study area (Figure 17 A) . The May and June 197 5
K4- values are approximate because of equipment problems re-
ported at Sachs Harbor. In July and August, 1975, the inci-
dent solar radiation at Sachs Harbor was less than during the
same period in 1974. This was due to the fact that there was
greater cloud cover in 1975 because of the larger expanse of
open water in the Southeastern Beaufort Sea. The cloud cover
was presumably even greater over open water, thus accounting
for the reduction in calculated incident solar radiation com-
pared to the observations at Sachs Harbor and Inuvik (Figure
16) .
When the solar radiation reaches the earth, part
of it is reflected and the remainder is absorbed. Solar
radiation has some capability of penetrating ice and water
[Maykut and Grenfell, 197 5] and to a lesser extent snow [O'Neill
and Gray, 1972] . The percentage absorbed is a function of
the albedo, A, which is an important factor in the heat budget
of the Arctic [Langleban, 1971] , and is a function of the
texture, wetness, and color of the surface, the angle of inci-
dence of the solar beam and atmospheric scattering. Albedo
usually increases with decreasing solar altitude and decreases
45
with increasing wetness. Snow and ice reflect most of the
sun's rays and have a high albedo. Water has a low albedo,
depending on the angle of incidence. The albedo is particu-
larly important in the Spring when the change from ice and
snow to water causes it to change suddenly. Table 1 shows
representative values of albedo over various surfaces (after
Sellers, 1965 and Orvig, 1970) . Note the change from snow
and ice (albedo 65%) to water in the summer (albedo 7%) . Thus
the net shortwave radiation is highly dependent on the effec-
tive albedo for the study area.
b. Longwave Radiation (L+ + Lt)
The net longwave radiation is the sum of the inci-
dent longwave radiation and the back radiation. The incident
longwave radiation L+ is also referred to as the downward
infra-red radiation and is the longwave radiation from the
atmosphere, from moisture, and carbon dioxide in the air, and
from clouds. The back radiation Lt is also known as the up-
ward infrared radiation and depends on the emissivity of the
surface and its temperature .
The expression used to calculate the net longwave
radiation is based on Sverdrup (194 2) :
L+ + Lt = e a T4(l - 0.44 - 0.08 /i") (1 - 0.083C)
(9)
where
e is the emissivity;
46
TABLE 1
Typical values of albedos over various surfaces
(after Orvig, 1970, Sellers)
Structure
Freshly fallen snow
Freshly fallen snow
Freshly drifted snow
Freshly drifted snow
Snow, fallen or
drifted 2-5 days
ago
Snow, fallen or
drifted 2-5 days
ago
Dense snow
Dense snow
Snow and ice
Melting ice
Melting ice
Snow, saturated with
water (snow during
intense thawing)
Water Content and Colour
dry bright-white clean
wet bright-white
dry clean loosely packed
moist grey-white
dry clean
moist grey-white
dry clean
wet grey-white
dry grey-white
wet grey
moist dirty grey
light green
Melt puddles in first light blue water
period of thawing
Melt puddles, 30
100 cm deep
Melt puddles, 30
100 cm deep
Melt puddles
covered with ice
Melt puddles
covered with ice
Water surfaces
Water surfaces
Soil
Soil
Soil
green water
blue water
smooth grey-green ice
smooth ice, covered with
icy white hoar frost
Winter 60 °N
Summer 60 °N
dark
moist grey
dry sand
Albedo %
Average
88
80
85
77
80
75
77
70
65
60
55
35
27
20
22
25
33
21
7
10
15
35
47
TABLE 1 (CONT.)
Structure Water Content and Colour Albedo %
Average
Cloud overcast cumuli-form 80
Cloud stratus 70
Cloud Altos tratus 49
Cloud Cirros tratus 47
48
a is the Stef an-Boltzman constant
(a = 1.18 x 1(T7 ly day"1 °K~4);
T is the surface temperature (°K);
e is the vapor pressure of the atmosphere (mb) ; and
C is the cloud amount (tenths) .
The surface temperatures are a minor source of
possible error since they were bucket temperatures or tempera-
tures measured at the sea-intake of the vessel. In any case,
they were not the skin temperatures required in Equation (9) .
The error could be even larger in calculations over ice sur-
faces where the temperature was assumed to remain at 0°C,
whereas considerable heating of melt water on the ice surface
can occur (see Section III.B.8). The vapor pressure, e, was
calculated using wet-and-dry bulb temperatures read from a
vessel's bridge and subject to errors due to the presence of
the vessel. Possible cloud amount errors arise due to errors
in reporting and the assumption that the cloud amount was the
same over the entire area.
c. Summary of Net Radiation Q*
Figure 17B compares the net radiation for 1974
and 1975. The net radiation Q* was significantly greater
early in 1975 than during the corresponding period of 1974.
This was presumably due to the greater expanse of open water
in early 1975 which reduced the effective albedo allowing more
radiation to penetrate the ocean. By mid- July, this effect
was reduced by the more extensive cloud cover over the study
49
area in July and August of 1975. By reducing K4-, the net
radiation was correspondingly reduced. In August, during the
period of marine observations there was a correspondence
between small Q* fluxes and onshore winds mainly due to the
increased cloud cover during those periods. With offshore
winds, clear skies usually persisted allowing larger amounts
of incident solar radiation K4- to penetrate.
The daily variation for radiation fluxes observed
in August is shown in Appendix B.
2. Latent Heat Flux Q^
hi
a. Evaporation
The rate of evaporation depends on the deficiency
of water vapor in the air immediately above the water surface
and the rate at which the air is mixed. Mixing depends on
the turbulence of the air, which is a function of wind speed
and thermal convection. The amount of evaporation is often
calculated from climatic data by the Sverdrup formula [Walmsley,
1966 and Huyer and Barber, 1970]. Thus,
E = K V (e__ - e ) (10)
w a
where E is the rate of evaporation of water (mm day ) ;
K is an empirical coefficient;
V is the wind speed (m sec ) ;
e is the water vapor pressure at the surface (mb) ;
e is the water vapor pressure in the air (mb) .
a
50
There are other equally good formulae, but because
Sverdrup's is so widely used it forms a basis for comparing
heat budget calculations for different regions. Furthermore,
in a summary of available evaporation formulae, Swinbank (1959)
concludes that no fundamental improvement over the Sverdrup
formula is available at present [Walmsley, 1966] .
It has been found that the coefficient K varies
with wind speed. The critical wind speed separating turbulent
and smooth flow is generally taken as 12 knots. Lacking any
information to the contrary, Walmsley' s (1966) procedure was
followed, where the evaporation coefficients for both water
and ice surfaces are:
0.145 , V > 6.2 m sec"1
K =
0.090 , V < 6.2 m sec
b. Vapor Pressure
Again, following Walmsley (1966) the Clausius-
Clapeyron equation may be written in the form:
M L
e = 6.11 exp[-^r(273 - |) ] (11)
where
M is the molecular weight of water vapor;
R* is the universal gas constant; and
M /R* = 9.08 gm cal"1 °K .
51
An explanation of the terms e, T, L in four
different situations is given below.
(1) For the vapor pressure at eight meters above
the surface:
e = e
a
T = T
' , the dew point temperature (°K); and
L = L^ , the latent heat of vaporization (cal gm )
(2) For the saturated vapor pressure just above
a water surface:
e = e
w
T = T , the sea surface temperature (°K); and
L = L .
v
(3) For the saturated vapor pressure just above
an ice surface:
e = e .
l
T = T. , the ice surface temperature (°K); and
L = L , the latent heat of sublimation (cal gm )
(4) For the saturated vapor pressure just above
a melt-water surface:
i
52
e = e .
1
T = T.
L = L .
v
It was further assumed that if the temperature were
greater than 0°C, the ice surface was a melt-water surface
(Case 4 above) , and if the temperature were less than or equal
to 0°C, Case 3 above applied. The values for latent heat
were taken from Hess (19 59) :
L = 597.3 cal gm ; and
L = 677.0 cal gm .
c. Latent Heat Flux
An expression for Q_ is
hi
QE = p L E (12)
where
-3
p is the density of water (gm cm ) ;
L is the latent heat (cal gm ) ; and
E is the rate of evaporation (cm day )
By combining Equations (10) and (11) and substi-
tuting into (12) , the latent heat fluxes can be calculated
using the observed meteorological data. Condensation is
interpreted as negative evaporation and is a downward flux.
53
Sublimation is considered the same as melting followed by
evaporation in the case of an upward flux, or condensation
followed by freezing for a downward flux.
The terms Q_ and L in Equation (12) are further
hi
defined for two particular cases:
(1) Evaporation over an open-water surface:
QE = QE (water)
i
L = Lv
(2) Evaporation over an ice surface or melt-
water surface:
QE = QE (ice)
L = L .
s
In this study, evaporation occurred from the sur-
face of the Southeastern Beaufort Sea which was always at
least partly ice-covered. The latent heat flux was calculated
for each surface separately and then a weighted average of
the fluxes over the ice surface and the open-water surface
was taken :
QE = QE (ice) (CONC) + Q£ (water) (1 - CONC) (13)
where CONC is the ice coverage in tenths .
Figure 17 C compares the latent heat fluxes for
1974 and 1975 in the study area. The fluxes were small in
54
both years but higher in 1975 due to the larger area of open
water over which evaporation could take place. In August/
the standard deviation of the calculated latent heat fluxes
for each wind condition is also shown. It can be seen that
there is great variability even under similar wind conditions.
Generally, though, onshore winds cause evaporation due to the
cold dry air blowing from the ice over the water. Offshore
winds result in condensation as the warmer continental air is
cooled and becomes saturated.
The daily variations in observed latent heat
fluxes for August of each year are shown in Appendix B.
3 . Sensible Heat Flux Q
The sensible heat flux at the surface depends mainly
on the vertical temperature gradient. Again, following
Walmsley (1966) and Huyer and Barber (1970), Shuleikin's (1953)
formulae were used to calculate the sensible heat flux. If
the surface temperature was warmer than the air temperature
(T > m j f Shuleikin (1953) used no wind factor in his formula
s a
for computing the exchange of sensible heat. The instability
in the air caused by the temperature gradient created suffi-
cient turbulence to maintain the mixing process. In this case:
Q„ = 30.24 (T - T ) for T > T (14)
u s a s a
where
T is the surface temperature (°C)
T is the air temperature (°C)
55
On the other hand, if the water were cooler than the
air, Shuleikin (1953) used Equation (15) where wind speed
was considered an important factor to maintain the mixing
in spite of the stable temperature gradient. In this case:
Q„ = 0.42 V(T - T ) for T < T (15)
H s a s — a
where V is the wind speed in (m sec ) .
It is also important to note that the Shuleikin
formulae (Equation (14) and (15)) were originally derived
for use over partially ice-covered water surfaces [Matheson,
1967] . In this study, the sensible heat flux over the area is
a weighted average of the fluxes over the ice surface and the
open water. The weighting is determined using an equation
similar to Equation (13) .
Figure 17D compares the sensible heat fluxes for 1974
and 197 5 in the study area. The fluxes were small in both
years, but the losses were slightly greater in 1975 because
of the higher water temperature and the greater expanse of
open water through which sensible heat could be lost from
the system. In August, the standard deviation of the calcu-
lated sensible heat fluxes for each wind condition are also
shown. In 1974, the greatest heat loss corresponds to the post-
northwest wind period. In 1975, the greatest heat loss corres-
ponds to onshore winds blowing cold polar air from the ice over
the study area. The daily variations in observed sensible heat
fluxes for August of each year are shown in Appendix B.
56
4. Atmospheric Heat Flux Q
From Equation (2) ,
QA = Q* + QE + QH (2)
Summing the individual fluxes discussed previously
gives the resultant atmospheric flux shown in Figure 18. A
comparison of the 1974 and 1975 fluxes shows that the heat
gain early in the season in 1975 was much greater than in
1974 due to the large expanse of open water into which solar
radiation could penetrate. This more than compensated for
the increased upward fluxes of Q_ and Q„ in 1975. From mid-
July to the end of the season, the atmospheric fluxes were
comparable in both years. In the month of August, standard
deviations of the mean atmospheric fluxes are shown for each
wind condition. In spite of the great variability, it can be
clearly seen that onshore winds, originating over the polar
pack, result in heat losses by the system. Offshore winds,
originating over the warmer continental land mass, cause heat
input to the system.
Figure 19 shows the accumulated heat content due to
the atmospheric fluxes starting from May 1. The large excess
of accumulated heat absorbed by the system by mid- June 197 5
remains about constant during the remainder of the study period
The values obtained for the atmospheric fluxes in the
Southeastern Beaufort Sea during the summers of 1974 and 197 5
were compared to results obtained by Walmsley (1966) in Baffin
57
Bay for the period 1919-194 2, and to the results obtained by
Huyer and Barber (1970) for Barrow Strait in 1962 (Figure 20) ,
which agree well with the present data. It can be seen that
in general in the Arctic Seas, the atmospheric fluxes reach a
maximum downward at about the same time as the maximum open
water, usually shortly after the summer solstice.
D. OCEANIC HEAT FLUX (STORAGE CHANGE) Qg
The storage change Q is defined in Equation (3) as the
9
summation of the individual oceanic fluxes such that:
Qs = QT + Q„ + Qp + Qj (3)
(see Section III. A for definition of terms). The accumulated
storage heat Q equals the time integral of the sum of the
oceanic fluxes such that:
Q_ = Qm + Q„ + 0^ + 0^ (16)
VS T W F I
(see Section III. A for definition of terms). Each term will
be discussed separately in the following sections. Figure 21
summarizes each flux term and Figure 22 summarizes the accumu-
lated heat terms. Further references will be made to each
of these figures in the applicable section.
1. Mackenzie River Heat Q
Mackenzie River water enters the Southeastern Beaufort
Sea through three main channels [Davies, 1975] . About one-
third of the flow enters Shallow Bay, about one-third enters
58
Kugmallit Bay, and the remainder stays in Middle Channel
until it reaches Mackenzie Bay in the vicinity of Richard's
Island. Figure 23 shows the annual variation for the year
1974/1975 of the thickness of landfast ice in Mackenzie Bay,
the river temperature, and the river discharge volume. It
can be seen that the landfast ice is about two meters thick
in May and remains at about the same thickness until breakup
in July, which follows closely after the peak freshet in early
June. The maximum river water temperature does not occur until
late July. The inter-annual variations in river-water tempera-
ture appear small [Fraker, 1979] . Discharge volumetric rates
vary only slightly from year to year [Herlinveaux, 1976] .
Since no discharge rates were available for the summer of 1975,
the discharge rates for 1972, a similarly good ice year, were
used.
The river's heat contribution, Q , was calculated by
multiplying the net discharge volume between particular dates
by the water temperature relative to the reference temperature
of -1.5°C. These quantities were both reasonably well known.
The river was assumed to be the only source of heat due to
water mass advection across the boundaries of the study area.
The deep water remains cold and contains little heat (if any)
relative to -1.5°C. The surface currents within the area
vary considerably but residual currents appear to be weak and
would cause little heat change by advection.
Figure 21A shows the variation of QT during each summer
season, and Figure 22 shows the accumulated heat contribution
59
Q . The major heat input occurs with the combination of
large discharge volumes and high temperatures about mid- July.
The heat from the river varies little from year to year and
18
remains about 2.2 * 10 g cal in both 1974 and 1975.
2. The Heat Used to Warm the Water in the Upper Layer
of the Ocean QTT
^W
The oceanographic data which were used in calculating
the heat content of the upper layer of the sea were collected
as part of the Beaufort Sea Project, a set of environmental
studies carried out in the Southeastern Beaufort Sea in 1974
and 1975 [Herlinveaux, 1976]. During the summer of 1974, pro-
files of salinity, temperature and turbidity were obtained from
MV THETA, an ice-strengthened vessel resembling a North Sea
trawler. Sixty-three stations were occupied during the period
August 12 to September 1, 1974 (Figure 24) . In the summer of
197 5, similar observations were made at forty-eight stations
during the period 5-24 August 1975 (Figure 25) . The water
temperatures versus depth at each oceanographic station in
these two years were used to determine the heat content of the
water column in the study area.
The calculation of this term depends on the mean layer
temperature above the -1.5°C isotherm and its depth. The
calculations were based on recorded CTD casts [Herlinveaux,
1976] . The heat content of the water column was generally
underestimated since it was assumed that the heat content
below the deepest temperature reading was zero (Section III.B.7)
In shallow water, where the temperatures were warm, considerable
60
error may have been introduced to a maximum of about 5%
underestimate of the heat content at any one time.
The oceanographic observations were then grouped into
Marsden sub-sub-squares (see Appendix I) and their respective
heat contents were averaged to obtain a heat content for each
sub-sub-square. These mean heat content values in each sub-
sub-square were summed to obtain the total heat content of the
study area at the time of the oceanographic observations in
August of each year. The heat content of the water column in
August 1974 was calculated at three different times corresponding
to each of the three different wind regimes. The corresponding
variation in Qw is shown in Figure 22. From these accumulated
values, the Q fluxes were determined by difference and are
plotted in Figure 21B which shows that the heat flux indicates
cooling of the water column during onshore winds and warming
of the water column during offshore winds (refer to Figure 11
for wind vectors) . A similar calculation could not be done
for August 1975 because the entire period of oceanographic sta-
tions was considered as a single synoptic period for purposes
of calculating the heat content Q . Thus Figure 21B shows the
flux Q = 0. In Figure 22, the accumulated heat Q„ in August
of each year can be compared. It can be seen that the heat
18
content of 4.4 x 10 g cal in 1975 was much higher than the
TO
heat content Q of 1.0x10 g cal in 1974. The change in
accumulated heat Q between May 1 and the time of the first of
the oceanographic measurements is unknown, and is not shown in
Figure 22. Because of this, the heat budget equation (Equation
61
(4)) can only be solved during the period of oceanographic
observations . Further information obtained concerning the
distribution of heat in the water column is shown in Appendix
D.
3. The Heat Due to Cooling or Warming of the Ice and
its Subsequent Freezing or Melting in Place Q
r
The ice coverage in the study area was determined from
available satellite imagery and ice charts. Satellite imagery
provided a semi-monihly look at the ice cover from May 1 until
the end of June, after which ice charts provided weekly infor-
mation until the end of September.
The calculation of Q„ was based solely on the determina-
£
tion of the ice coverage and concentration to determine the
amount of heat lost in melting a certain area of ice-in-place.
Based on the assumption of Section III.B.8, the heat required
to raise the temperature of the ice from -7°C to 0°C and sub-
sequently to melt the ice is the latent heat of fusion of
-1 2
approximately 79 cal gm . The heat required to melt 1 km
15 -2
of two-meter thick ice would be 0.15 x 10 g cal km . Since
2
the total study area is 46,794 km , the heat required to melt
a given area of ice can be quickly determined from Figure 26,
which shows the relationship between ice coverage in the study
area and the heat content Qp. For example, if the ice coverage
observed throughout the study area were six-tenths, the heat
Q„ used to melt the ice to obtain that open-water area by
18
melting-in-place would be 3.1 * 10 g cal.
Errors may arise due to unobserved changes in the ice
cover which would result in changes in the effective albedo
62
of the area. Another possible error is that the ice is assumed
to melt-in-place . This means that a decrease in the ice cover
observed from one ice report to the next was assumed to be the
result of melting only. If these changes in the ice cover
were instead due to ice advection, the error introduced in
this term would be balanced by a change in the ice advection
term Q (see Section III.D.4) . For example, if the ice cover
in consecutive ice reports was seen to change from three-tenths
to one-tenth, it would be assumed that the change was strictly
due to the melting of two-tenths ice-in-place, rather than any
combination of melting and advection. Figure 21C shows the
heat fluxes Q_ corresponding to the observed ice coverage
throughout the season. It can be seen that early in the
season in 1975 there is a long period of decreasing ice cover-
age which led to the good ice conditions of that year; whereas,
in 1974 in late May and early June the ice coverage was still
increasing.
The accumulated heat QF is shown in Figure 22 and
corresponds directly to the plot of open water area shown in
Figure 10. Because the area of open water was much greater
in 1975, the heat used to melt the ice-in-place was also much
greater in 1975. The peak open-water period in 1975 occurred
in the latter part of July, after which predominant northwest
winds imported ice at a rate which exceeded the melting rate
so that the open-water area decreased until the end of the
season. There was a time lag of about one week at the end of
63
August between the minimum value of Qp and the minimum value
of the heat content of the water column Q .
In 1974, the time for the maximum open water did not
occur until mid-September after a prolonged period of easterly
winds had made more heat available to melt the ice and to export
it from the study area.
4 . Heat Due to Ice Advection Q
As was previously indicated in Section III.B.8.e., the
ice advection term, QT/ together with Q_ are determined by
JL t
difference. Q therefore contains all of the errors in the
other terms. Nevertheless, it will be seen that it is of
plausible magnitude, consistent between the two years and
properly correlated with wind effects. If Q_ is a positive
flux, it represents a volume of ice being imported, since that
represents a heat loss to the system in that the entire volume
imported ice must be melted so that the ice coverage does not
change. If Q is a negative flux, it represents a volume of
ice being exported, since that represents a heat gain to the
system such that the volume of exported ice did not require
heat from the system to melt the ice to obtain the ice cover-
age observed. Figure 21D shows the calculated Q fluxes for
the period of oceanographic observations in each year during
which Equation (5) could be solved. It can be seen that in
August of 1974, the rate of ice export increased during the
month, accounting for the increase in open-water area. Figure
22 shows the values for accumulated heat due to ice advection
Q_. It can be seen that in both years, there was a net import
64
of ice throughout the season. In August 1974, the QT term
is diminishing corresponding to an export of ice, especially
at the end of the month. This is to be expected since the
known winds were blowing offshore at this time and were pushing
ice out of the study area. In August, 1975, there was continu-
ous ice import (Figure 21D) , accounting for the decrease in
open-water area. Also, the Q term (Figure 22) is increasing
corresponding to ice import. Thus the onshore direction of the
winds during most of the latter part of August 1975 seems to
have imported ice to the area.
The two curves of QT (Figure 22) cross each other in
the last week of August at about the same time that the plot
of open water (Figure 10) shows equal ice coverage in the
study area. This occurs in spite of a vastly greater area of
open water in July /August of 1975. Therefore there must have
been a rapid import of ice during August 1975 due to the pre-
vailing northwesterly winds (Figure 11) .
The values obtained for Q_ represent a volume of
advected ice. Using a calculation similar to that done in
Section III.D.3 to calculate the heat of fusion of ice,
15 2
0.15 x io g cal represents the advection of 1 km of two-
meter thick ice. Table 2 shows the estimated ice areas
advected based on the calculation of Q_.
E. SUMMARY OF THE HEAT BUDGET EQUATION
An example heat budget calculation was done for August 15
of the years 1974 and 1975 based on the values of the heat
65
TABLE 2
i1 m18
g cal x 10
change in Q_
i mis1
g cal x 10
ice area
advected
km2 x io3
1974 August 12
August 31
11.5
9.4
-2.1
-13.0
197 5 August 5
August 24
7.6
10.8
+3.2
+20.0
(-) export of ice
(+) import of ice
budget terms assuming that all the heat started accumulating
on May 1. The resulting heat budget equation is shown in
Figure 27.
The greatest difference in the heat inputs from May 1 to
August 15 was the net radiation term Q* . The appearance of
open water and subsequent wind-mixing early in the season in
1975 during the period of maximum insolation allowed large
quantities of radiation heat to be absorbed by the water column
This in turn made more heat available to the system to be used
to melt ice (Q_) . With more open water in 1975, the river
heat, Q_, was allowed to spread over a larger area, rather
than being dammed up by the ice as it was in 1974. The sensi-
ble heat, Q„, and the latent heat Q_ were about the same in
rl hi
each year and were roughly equal to the input of heat from the
66
Mackenzie River. The energy loss due to conversion of energy
into stored heat in the upper layer of the ocean, Qw, was
larger in 1975 as shown by the deep warm surface layer (see
Appendix D) . In 1974, the heat was restricted to a thin layer
about 5-10 meters deep. A difference was that in 197 5 increased
turbulent mixing early in the season allowed the heat to be
absorbed to much greater depths. The remaining ice advection
term, Q , used to balance the equation shows net ice import
in both years. In spite of the import of ice in 1975, there
was sufficient heat excess to keep the study area mainly ice-
free throughout the month of August , thus making it a good
ice year, in contrast to 1974 when there was insufficient
heat in the water column to keep the area ice-free, thus
making it a severe ice year.
67
IV. CONCLUSIONS
Data gathered during the Beaufort Sea Project in the
summer of 1974 (a severe ice year) , and in the summer of
1975 (a good ice year) were displayed and analyzed with
special attention to the heat budget terms and the related
heat fluxes. The heat budget equations were computed for
each summer period and comparisons made to determine the
relative importance of the various fluxes . The following
conclusions resulted:
A. The major source of heat to the study area, regardless
of the severity of the ice, is the contribution from solar
radiation. However, the net radiation was a factor of two
greater in 1975 (a good ice year) than in 1974 (a severe ice
year) due principally to the much larger area of open water
in 1975.
B. The wind pattern in early spring is critical in the
final outcome of the heat budget. Offshore winds will produce
an early breakup, allowing the large fluxes of incident solar
radiation to be absorbed in the sea. iOnshore winds (primarily
from the northwest) press the pack-ice nearer the shore, causing
most of the incident solar radiation to be reflected by the
ice cover.
C. The wind patterns later in the summer are the major
factor in determining the ice coverage by controlling its
advection. Persistent offshore winds in the latter part of
68
August 1974 were responsible for a greater open-water area
in September 1974 than was observed at the same time of year
in 1975.
D. The heat contribution from the Mackenzie River varies
little from year to year and is only about 10% to 20% of the
heat input due to the net radiation . The river heat is
responsible for local breakup in the vicinity of the Delta,
but has negligible impact beyond the shelf.
69
1
APPENDIX A
SUMMARY OF MARINE SURFACE OBSERVATIONS
Figures 28 through 33 summarize the observations of air
temperature, water temperature, dew point temperature, cloud
amount, wind speed and wind direction as provided in the
marine meteorological records obtained from the National
Weather Records Center at Asheville, North Carolina.
The reader is reminded that these observations were from
vessels operating on their preferred routes in the study area
and that sequential observations may have been reported by
different vessels operating at opposite ends of the study
area under different meteorological conditions. Changes in
water temperature, for example, are as likely due to a change
of location of a vessel as an actual change in temperature
at one location. Wind speed and wind direction tend to be
consistent throughout the study area as supported by observa-
tions from drill ships in the Southeastern Beaufort Sea in
later years [Milne, 1980].
70
APPENDIX B
DETERMINATION OF DAILY FLUXES IN AUGUST
The calculated atmospheric fluxes of sensible heat Q.,,
n
latent heat Q , net radiation Q*, the resultant atmospheric
St
flux QA, and the relationship of atmospheric flux Q_ to wind
direction are shown in Figures 34 through 39 for August of 1974
and in Figures 40 through 45 for August of 1975. Figure 46
summarizes the daily average atmospheric fluxes Q_ for August
of each year. Figure 47 compares the accumulated atmospheric
heat Q for August of each year showing the effects of ice
cover on Q .
1 . Assumptions
The meteorological observations of Appendix A pro-
vided the raw data for calculating the atmospheric fluxes using
Equations (7) through (15) as discussed in Section III.C.
Three different assumptions were made, resulting in three
sets of curves.
a. Open Water
It was assumed that the marine observations were
taken in open water and that the calculated fluxes represent
those which would have existed under the given environmental
conditions if no ice were present.
b. Ice Covered
It was assumed that the marine observations were
taken over an ice surface; that is, in effect a sheet of ice
71
was simply slid into place with no modification of the air
mass overlying it.
c. Averaged over the Entire Area
During the study period, there was a known ice
coverage in the study area at any given time. It was not
known, however, what ice concentration existed at the reporting
point. Since it was assumed that the observation was represen-
tative of the conditions over the entire study area at that
time, the effects of ice had to be considered. This was done
in each case with Equation (17) (similar to Equation (13)),
where Q represents any atmospheric flux term.
Q = Q(ice) (CONC) + Q (water) (1 -CONC) (17)
2. Results
The main features of the graphs of atmospheric fluxes
were consistent regardless of the source of the radiation
values. A summary for each element of the atmospheric flux
term Q, based on each of the above assumptions follows,
a. Sensible Heat Flux Q„
Over open water, QH is directed upward (.+ ) repre-
senting a heat loss to the system. Over ice, the flux is
directed downward (-) representing a heat gain to the system
Similar graphs were drawn based on observations at Sachs
Harbor and Inuvik. These are not included in the discussion
since no new information was gleaned from them. They showed
the same directions of fluxes and same trends, although the
magnitudes differed slightly.
72
whenever T is greater than 0°C (which it is for most of
a
August) . When averaged over the entire area, the direction
of flux turns out to be dependent on the wind direction:
Onshore winds cause upward QH; offshore winds cause downward
Q . During onshore winds, cold, dry air blows across the ice
towards the open water of Mackenzie Bay. If air temperatures
are only slightly above freezing, very little air mass modi-
fication will take place until the winds blow over the water,
at which time the cold air will warm and absorb large quanti-
ties of heat from the water column. When offshore winds blow,
warm, continental air moves over the water. The air mass near
the surface cools quickly to the water temperature to produce
a stable, saturated air column which inhibits the sensible
heat transfer, and results in a small downward transfer of
sensible heat (a heat gain by the ocean) .
b. Latent Heat Flux Q
Over open water QE is generally directed upward
( + ) (a heat loss from the system) . Over ice, the flux is
directed downward (-) as condensation occurs over the ice
surface. When averaged over the entire area, the direction
of flux again appears to be dependent primarily on wind
direction: onshore winds cause evaporation and upward Q ;
offshore winds cause condensation and downward Q„. The reason-
ing is similar to that given above.
c. Net Radiation Flux Q*
Over open water, Q* is generally directed downward
because of the low albedo of the water. Over ice, it tends
73
to be directed upward because of the high albedo of the ice.
When averaged over the entire area in August 1974, except
when the cloud cover was less than three-tenths, Q* was directed
upward because of the extensive ice coverage. In contrast,
in August 1975, there was a greater open water area, and as
a result, the curves for the open-water case and the entire
area were very similar showing a general downward direction
decreasing in magnitude as the season progressed and the
incident solar radiation K + decreased.
d. Atmospheric Flux Q
These curves are the summation of each of the
three previous curves for any particular case. The most
striking feature is the dependence of direction of flux on
wind direction which shows up in all cases. With onshore
winds, Q- is directed upward (heat loss from the ocean); with
offshore winds Q, is directed downward (heat gain by the
ocean) . This dependence is pictured more graphically in
Figures 39 and 45 which plot heat flux Q versus wind direction
for August 1974 and August 1975 respectively. To the left of
the zero line represents a heat gain by the ocean. Notice
that the major heat gains occur for offshore winds. The major
heat losses occur during onshore winds, most notably north-
westerly winds.
3 . Summary
The results obtained for the atmospheric flux Q are
summarized in Figure 46, showing the curves based on two of
the assumptions, la, and lc. (Since few observations were
74
likely taken in total ice cover, this case, lb, is not shown.)
Two features should be noted:
a. the heat losses are almost always greater over
open water than averaged over the entire area, probably
because the water is warmer and has more heat to lose;
b. the direction of heat loss is determined by wind
direction (onshore or offshore) .
The calculated daily fluxes for August were summed
to obtain the net accumulated heat Q for each day of the
month, using the first day of observations in each year as
the zero point. The following features of Figure 4 7 are
noted:
a. the accumulated heat loss over water is greater
than that averaged over the entire area;
b. in August of both years there was a net loss
during the month over the open-water area but a net gain of
heat through the ice which resulted in a net gain of heat
over the entire area; and
c. although the open-water area in August 1974 was
less than in 1975, the loss of heat through that area was
greater due to cooler air temperatures.
75
APPENDIX C
EXTREME VALUES OF HEAT FLUXES AND
ASSOCIATED ENVIRONMENTAL CONDITIONS
Tables 3 through 6 inclusive list extreme values of
atmospheric heat fluxes and the conditions that existed
when they occurred.
1 . Maximum Upward Fluxes
Table 3 summarizes the maximum upward fluxes as
calculated over open water. Maximum sensible heat losses
occurred during northwest winds, with cold polar air blowing
over warmer water, and clear skies. The maximum latent heat
losses were also found during northwest winds but in this
case cloud amounts were moderately high at 7/10. The maximum
net radiation flux also occurred during northwest winds and
overcast skies. Finally, the maximum atmospheric flux Q_
occurred under identical conditions to the maximum latent heat
loss, suggesting that the latent heat flux was a major contribu-
ting factor to high heat losses at the surface.
Table 4, summarizes the maximum upward fluxes as
averaged over the entire area, taking into account the ice
coverage at the time . Because of the small upward fluxes over
ice, the extreme values over the entire area were generally
less than those over open water alone. The exception is the
net radiation where the high albedo of the ice cover increased
the upward radiation flux.
76
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78
2 . Maximum Downward Fluxes
Table 5 summarizes the maximum downward fluxes as
calculated over open water. Maximum sensible heat gains
occurred when winds blew offshore from 120° to 190° at
fairly high speeds (23-32 knots) , blowing warm, dry air from
the land over the colder water. The sensible heat fluxes
under these conditions seemed to be independent of the cloud
amount. The maximum latent heat gains occurred under the
identical conditions as the largest values of downward sensi-
ble heat flux. The maximum net radiation flux occurred under
clear skies. Finally, the maximum atmospheric flux QA occurred
under the identical conditions as the maxima of sensible and
latent heat fluxes above. This indicates that the warm, dry,
continental air was a major factor affecting the heat budget
of the Southeastern Beaufort Sea.
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averaged over the entire area, taking account of the ice
coverage at the time. Because of the large downward fluxes
over the ice, the magnitudes of the extreme values were
generally greater than those over open water. The exception
is the net radiation where high albedo of the ice cover
increased the upward radiation flux.
79
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81
APPENDIX D
DISTRIBUTION OF HEAT IN THE STUDY AREA
1. Summer of 1974
As discussed previously, the 1974 data has been
divided into three groups corresponding to the three synop-
tic conditions encountered during the study period; northwest
winds from August 9 to 20; post-northwest winds from August
20 to 24; and easterly winds from August 25 to September 1.
The following observations are noted.
a. Northwest Winds
During northwest winds, the pack-ice was pressed
toward shore by the wind. Also, the surface currents close
to shore tended to flow east following the coastline as
shown in Figure 48 [MacNeill and Garrett, 1975] . The ice
edge advanced southward into Mackenzie Bay south of Herschel
Island. The heat content was highest at the mouth of the
river as might be expected (Figure 49) . Surface temperatures
during this period ranged as high as 8 °C in places . The
-2
maximum heat content of 6 kg cal cm ' was located midway between
Herschel Island and Pullen Island (Figure 49) . The reason for
this concentration of heat is unknown. However, it appears
that this area of maximum heat content would have been the
optimum position between the shallow, shelf waters which were
bottom- limited in gaining more heat from the river and the
deeper water near the ice-edge where heat was extracted from
82
the water in melting the ice. The river plume is well marked
by the contours of the heat content. Figure 50 shows that
the mean layer temperature was over 3°C near the river mouth.
Figure 51 shows how the depth of the -1.5°C isotherm increases
to seaward. Toward shore, in the shallow water over the shelf,
the -1.5°C isotherm was bottom- limited,
b. Post- northwest winds
In the short period after the northwest winds
stopped blowing, a relaxation seems to have taken place. For
example, the surface currents immediately north of Richard's
Island completely reversed direction form northeast to south-
west (Figure 52) . There was also a relatively strong westward
flowing surface current from Shallow Bay to Herschel Island.
The ice edge retreated slightly, especially in the vicinity of
the warm core mentioned in the previous section. The contours
of heat content moved shoreward, pushing the available heat
in the water closer to shore (Figure 53) . The mean temperature
of the layer (not shown) had been similarly changed with the
0°C mean layer temperature paralleling the ice edge.
This short period of three days represents a
transition stage between the northwest winds and the easterly
winds. Figure 54 shows the onshore and offshore movement of
Mackenzie River, water due to these wind conditions. Because
of the time lag in the water column, the heat content during
this post- northwest wind period more closely resembles the
situation during northwest winds in Figure 54 with the warmer
83
Mackenzie River water pressed near the shore. The corres-
ponding heat content under conditions of easterly winds is
discussed in the following section,
c. Easterly Winds
During the period of easterly winds from August 25
to September 1, the surface currents all flow westward (Figure
55) as might be expected [MacNeill and Garrett, 1975] . The
heat content of the water (Figure 56) reflected the shifting
of the upper five meters of warmer, less saline water as it
slid over the deeper, colder, more saline water in response
to the wind. There was a significant change in the edge of
the ice pack as it retreated seaward north of Herschel Island.
The Mackenzie River plume re-asserted itself to the northwest
of Shallow Bay and a second tongue of warm water extended
north of Richard's Island. The residual cold water was con-
centrated in a small area near Kay Point where the temperature
of the surface water was less than 1°C.
Another feature not observed before lies north
of Atkinson Point on the Tuktoyaktuk Peninsula. A tongue of
warm water extended into the study area from Amundsen Gulf.
This is believed to have been due to solar heating of the
open-water area in the vicinity of the Bathurst Polynya. This
area was ice-free much earlier in the season and was heated
by solar radiation and wind-mixed to a greater depth than else-
where. The easterly winds also tended to move this feature
westward. This concept is supported by the depth of the -1.5°C
isotherm shown in Figure 57. North of Atkinson Point, although
84
the mean layer temperature (Figure 58) is less than 0°C,
the depth of the -1.5°C isotherm was over twenty-five meters
so that there was a thick layer of cool water containing more
heat than the thin layer of warmer water in the Delta area.
The plumes of river water are readily identified in Figure 58
by the contours of mean layer temperature.
2. Summer of 1975
The data for 1975 are presented in a similar manner to
that above. First, the month of August is examined in three
different wind conditions: strong northwest winds from
August 5 to 13; variable winds from August 13 to 19; and light
northwest winds from August 20 to 24. Finally, the data from
August 5 to 24 is looked at in total as a synoptic picture
of the study area.
a. Strong Northwest Winds
During strong northwest winds, the surface currents
flowed about the same as in August 1974 under similar wind
conditions (Figure 48) . In 1975, however, there was a much
greater expanse of open water and more mixing occurred in the
water column. Figure 59 shows the heat content in the study
area during this wind condition. The pack-ice edge was on the
northern boundary of the study area. The greatest heat content
in the water was in the eastern portion of the study area.
This supports the hypothesis made earlier that solar radiation
incident on the large open-water area north of Cape Bathurst
was responsible for early heating of the water column. Even
though the upper layer temperatures were not high, the warm
85
water was deeply mixed giving it a high heat content. Figure
60 shows the mean layer temperatures, which were warmest near
the river mouth, and gradually cooling as the ice edge
approached.
b. Variable Winds
With the cessation of the northwest winds, there
was a relaxation similar to that seen during the post-northwest
period of August 1974. A similar current pattern was also
established [MacNeill and Garrett, 1975] . The edge of the
ice pack retreated to the north. The limit of open water also
retreated to the north except in the west where it moved into
Mackenzie Bay from west of Herschel Island (Figure 61) . The
greatest heat content in the water was north of Atkinson Point
near the ice edge, but covering a much smaller area than during
the northwest winds the week before. Figure 62 shows the mean
layer temperature contours which roughly parallel the ice edge.
The warmest water was near the river mouth in Kugmallit Bay
but because it is so shallow, its heat content was less than
that in the northeast part of the study area.
c. Light Northwest Winds
Light northwest winds brought a rapid drop in the
air temperature resulting in the advection of ice into the
area and reduced ice melting. The heat content of the water
was greatly reduced from the previous period as it was chilled
by imported ice (Figure 63) . The river plume is clearly marked
in Figure 64 by the 6°C contour of mean layer temperature.
86
Unfortunately, there were no data during this time period in
the eastern half of the study area.
d. Synoptic Picture of August 197 5
Figure 65 shows the heat content of the study
area based on all available oceanographic data between August
5 to 24, 1975. The southern boundary of the polar ice-pack
is marked by a series of X's. The average August position
of the northerly limit of ice free water is marked with a
dashed line. Two warm cores stand out. One is in the east
and was probably a result of early season heating in the
Bathurst Polynya. The second was northeast of Herschel Island
and was probably caused by river run-off.
The mean layer temperature contours shown in
Figure 66 confirm that the plume of warm river water contributes
to the core of heat northeast of Herschel Island. As might be
expected, the mean layer temperature decreases as one moves
north from the coast to the ice-edge.
The depth of the -1.5°C isotherm is shown in Figure
67. Where waters are shallow closer to shore, temperatures of
-1.5°C are not reached so that the depths shown are the depths
of the deepest temperature measurements which were used in
calculating heat content. The 25-meter and 30-meter depth
contours of the -1.5°C isotherm exhibit an undulation northwest
of Richard's Island. This feature is caused by a cold intru-
sion of Arctic surface water which will be discussed further.
The greatest depths to the -1.5°C isotherm are found in the
vicinity of the highest heat content, indicating significant
87
absorption of solar radiation and probably substantial wind-
mixing in the open-water area to carry the heat to such great
depths.
Figures 68, 69, 70 and 71 show temperature con-
tours at depths of 5m, 10m, 15m, and 20m respectively which
exhibit features of the heat distribution at those depths.
At a depth of 5 meters (Figure 68) , a plume of 8°C water extended
northeast from Shallow Bay and another plume of 8°C water
extended from Kugmallit Bay, also in a northeasterly direction.
These high temperatures were from river water flowing out of
the various channels of the Mackenzie River. In fact, in the
river itself, temperatures reach as high as 20 °C. Also in
Figure 68, a core of cold water is evident just north of Richard's
Island indicating that upwelling had occurred and that there
was an inshore movement on the shelf of cold Arctic surface
water from beyond the continental shelf. (The appearance of
this feature is based on a single observation at Station 38,
is not supprted by any additional observations, and may be
a bogus feature.)
Figure 69 shows the temperature contours at a depth
of 10 meters with features similar to those described at the
5-meter depth. Figure 7 0 shows the temperature contours at
a depth of 15 meters and reveals several new features. A
plume of 4°C water extended northeast of Shallow Bay associated
with the 8°C plume at 5-meters depth. A second 4°C plume
north of Kugmallit Bay is associated with the 8°C plume found
88
there. The 4°C contour continues to the far northeastern
sector of the study area and reflects the existence of the
warm water area north of Atkinson Point associated with early
season heating in the Bathurst Polynya. Figure 70 also shows
a core of cold water (less than -1.5°C) northwest of Richard's
Island. This core of cold water could be a possible source
of the cold water core seen at 5-meters depth north of Pullen
Island. The reasons for its existence are not yet clear, but
studies of bottom currents in the vicinity support an on-shelf
motion at this depth [Milne, 1980] .
Figure 71 shows the temperature contours at 20
meters depth. A large portion of the study area is bottom-
limited at this depth. The warm plumes of river water noted
above are barely discernible at this depth. The core of cold
water (less than -1.5°C) northwest of Richard's Island is even
clearer at this depth. Figure 71 also shows the extent of
the warming of the water column in the northeastern part of
the study area. Even at 20 meters, the temperature exceeded
4°C.
3 . Comparison of Heat Distribution, 1974 and 1975
a. The surface current regime during northwest
winds was similar in both years.
b. The surface current regime after northwest winds
showed a similar relaxation in both years.
c. The heat content of the water was much higher in
1975, a good ice year, than in 1974, a severe ice year.
89
d. A warm water core in the vicinity of 70°N, 138 °W
existed in both years and with a comparable heat content.
e. A core of warmer water north of Atkinson Point
apparently associated with the Bathurst Polynya was evident
in both years.
f. The depth of the -1.5°C isotherm was a maximum
of 15 meters in 1974, but extended to a depth of over 50
meters in 1975.
g. The maximum observed sea surface temperature in
1974 was 8.08°C at Station 11 on 17 August east of Herschel
Island (Figure 24) . In 1975, the maximum observed sea surface
temperature was 8.70°C at Station 39 on 20 August north of
Richard's Island (Figure 25). Both Stations were on the
continental slope in about 60 meters of water. In spite of
the great difference in severity of the ice, there was little
difference in the maximum observed sea surface temperatures.
h. The thickness of the surface wedge of fresh, warm
water was greatest near the Delta and decreased as the ice
edge was approached.
90
APPENDIX E
SELECTED PROFILES AND CROSS-SECTIONS
1. Temperature , Density , and Salinity Profiles
Figure 72A shows the temperature, density and salinity
profiles at Station 12 (see Figure 24 for location) which is
typical of profiles seen in August 1974. Note that the thermo-
cline, the halocline, and the pycnocline all lie between five
and ten meters depth. There was a warm, fresh layer of water
overlying the very cold saline water below. This thin layer
of freshwater contained virtually all of the heat in the water
column and carried it about under the direct influence of the
winds and the river water movement. There was apparently very
little mixing across the interface. Using the reference tem-
perature of -1.5°C as the base depth of the layer for the pur-
poses of calculating heat content, the layer depth at Station
12 in 1974 was 15 meters. That is, all the heat was in the
top 15 meters of the water column.
This is in marked contrast to Figure 72B which shows
the profiles at Station 13 (see Figure 25 for location)
typical of a good ice year. The water at the surface was
more saline and the gradients of temperature, density and
salinity were more gradual. The heat had been mixed to a
much greater depth. Using the reference temperature of -1.5°C
as the base depth of the layer, the layer depth in 1975 was
27 meters, almost twice as deep as in a severe ice year.
91
2 . Cross-section A
Figure 73 shows the location of cross-section A
comprising Stations 20, 23, 24, 25, 26, and 27 during the
period of August 21 to 23, 1974. The cross-section itself is
shown in Figure 74. Along the coast, southeast of Herschel
Island the water was still very cold (below 1°C) right up to
the surface. Then to the east, a tongue of warmer, lower
salinity water was encountered with surface temperatures up
to 1.68°C. Further east, a tongue of much warmer and fresher
water (4.43°C) was encountered. At Station 29, still further
east (not included in the cross-section) warm water with sur-
face temperatures over 6°C was encountered in the shallow
inshore regions of eastern Mackenzie Bay. Below seven meters
there was very little change in temperature except as the
bottom shoals toward the east. At Station 28, the deepening
of the -1.5°C isotherm can be easily seen. The density cross-
section shows a marked pycnocline at eight to ten meters where
the sigma-t rapidly changed from 5 to 20 due to the layer of
fresher water (from river run-off and ice melt) overlying the
oceanic water. The density structure was well-stratified.
3 . Cross-section B
Figure 73 shows the location of cross-section B north
of Richard's Island comprising Stations 41, 53, 54 and 57
taken during the period from August 25 to 30, 1974. The
cross-section itself is shown in Figure 75; it shows the
changes from close inshore off Richard's Island (depth 10 m)
92
northwest across the shelf to the edge of the continental
slope. In the upper five meters, the effects of river run-
off can be seen. The surface temperature at Station 41 was
5.18°C, gradually decreasing to almost 0°C at Station 54
near the ice edge. The most notable feature is the large
mound or intrusion of water colder than -1.5°C between Station
53 and Station 57. This water appears to be Arctic surface
water originating from the continental slope region of the
Southeast Beaufort Sea.
The fresh-water effects can be seen in the density
cross-section to diminish as the distance from shore increases
This near fresh-water layer was about eight meters deep at
Station 41 and only about two meters deep at Station 57. The
density contour (sigma-t = 24) follows very closely the
temperature contour (T = -1.5°C) to outline the mound of cold
water.
4 . Cross-section C
Figure 73 shows the location of cross-section C
north of Tuktoyaktuk Peninsula comprising Stations 44, 45, 46,
47, 48, 49, 50, and 51 taken during a twenty hour period of
August 26 to 27, 1974. The cross-section itself is shown in
Figure 76. Because of the large number of stations taken over
a relatively short time span, this cross-section provides a
reasonably synoptic picture of the water column. Two shallow
tongues of warm, relatively fresh water can be seen centered
on Stations 45 and 51 respectively, but with a thickness of
only a few meters. The 0°C isotherm is almost horizontal at
93
five-meters depth. The -1.5°C isotherm slopes with the bottom
contours to a depth of about 20 meters. The density structure
shows a fresh-water wedge gradually shoaling to the north.
There was a marked pycnocline at a depth near five meters.
5. Cross-section D
Figure 77 shows the location of cross-section D east
of Herschel Island comprising Stations 45, 46, 47 taken during
the period of August 21 to 22, 1975. The cross-section itself
is shown in Figure 78, as it starts near the coast and goes
northward to the deep water on the continental slope. It can
be seen that mixing was greater than in cross-section A of
1974 (Figure 74) . The wedge of warm water extended both
deeper and further seaward. Also the heat content of the
water was much greater. The density cross-section shows deep
mixing compared to 1974. The surface water, although fairly
fresh, had a sigma-t of almost twelve. The wedge of near-
fresh water is still noticeable, but not as obviously as in
1974.
6. Cross-sections E, F, G
As in 1974, there is similar evidence of cold Arctic
water intruding toward Richard's Island in the summer of
1975. Used in the foloowing description are three vertical
cross-sections, each of temperature and density, from loca-
tions shown in Figure 76.
a. Cross-section E
Figure 79 shows cross-section E comprising Stations
41, 42 and 43 taken on August 20 and 21, 1975. The warm river
94
water extended a considerable distance seaward. Sea surface
temperatures decreased from 8.61°C at Station 43 to 3.65°C
at Station 41. There was a steep thermocline at about five
meters depth where the temperature decreased from 7°C to
4°C. In shallow water, it appears that considerable mixing
occurred right to the bottom, where the temperatures exceeded
3°C. The density cross-section also shows the mixing in
shallow water. Surface sigma-t values were about 10-12 with
a weak pycnocline at about seven meters. Cold, dense sea-water
had intruded onto the shelf to a depth of about 25 meters.
The cold intrusion of Arctic water does not manifest itself
in this cross-section.
b. Cross-section F
Figure 8 0 shows cross-section F comprising Stations
11, 12, and 13 taken on August 13 and 14, 1975. This cross-
section slices through the cold water intrusion discussed
above. A wedge of warm water extended seaward and cooled from
6.90°C to 4.97°C at the surface. The warm water was well-
mixed to a depth of about 20 meters to a position midway between
Stations 11 and 12. Here, there appears to have been a sharp
thermocline where the temperature decreased from 4°C to -1.5°C.
The cold, dense mound of sea-water is seen to have pushed its
way onto the shelf between Stations 12 and 13. Its position
coincided with the position of the cold intrusion identified
in cross-section B of 1974 (Figure 75) .
The density structure shows that there was con-
siderable downward mixing of the near-fresh water layer. The
95
minimum sigma-t was 10. The sigma-t equals 25 contour was
almost coincident with the -1.5°C isotherm and formed a
distinct boundary to the cold water intrusion.
c. Cross-section G
Figure 81 shows cross-section G comprising Sta-
tions 38, 39, and 4 0 taken on August 20, 197 5. This cross-
section is from stations occupied a week later than for those
of cross-section F and also intersects the cold water intru-
sion. Surface temperatures show a reversal in that they in-
crease as one proceeds seaward. The temperatures at Station
38 (just north of Richard's Island) were much cooler than those
further seaward. At Station 39, a surprising maximum of 8.70°C
marked the southern edge of a large shallow tongue of 8°C
water (see Figure 68) . The cold intrusion is also seen located
between Station 39 and 40. Directly above the cold intrusion
is a sharp thermocline where the temperature dropped from
8°C to 1°C in a depth increase of less than three meters.
The density structure does not reflect the features
mentioned above. The water column was strongly but evenly
stratified showing an almost horizontal sigma-t contour of
10 at about four-meters depth with no concentration of iso-
pycnals.
7 . Cross-sections H, I, J, K
These four cross-sections (Figure 77) are used to
examine more closely an area of high heat content north of
the Tuktoyaktuk Peninsula in the vicinity of the Bathurst
96
Polynya (Figure 65) . These cross-sections are for a region
of open water that was ice-free early in the season (as hinted
by the profile at Station 5) so that solar radiation was
absorbed to heat the water column. Later, as air temperatures
dropped, the surface layers would cool first possibly leaving
a warm, interstitial layer; however, it is more likely that
the temperature inversions described below were due to
surficial cooling by ice.
a. Cross-section H
Figure 8 2 shows cross-section H comprising Sta-
tions 22, 23, 24, 25 taken during the period of August 16, 17,
1975. It marks the westernmost limit of the thick warm water
feature. At station 24; a lens of warm 6°C water can be seen
to begin. It will be seen in the following cross-sections
that this feature extends northeastward from there. Only a
hint of the deep mixing exists at Station 24 where 6°C water
extends from five to eighteen meters depth.
b. Cross-section I
Figure 83 shows cross-section I comprising Sta-
tions 27, 28, 29, and 30 taken on August 17 and 18, 1975.
Stations 28 and 29 intersect the feature showing clearly a
deep layer of 5°C water at about 15 meters depth with colder
water above and below it. Even at Station 27, close to the
ice edge, a layer of warm water, albeit only 3°C, existed
between 15 and 20 meters deep. Surface cooling had apparently
occurred during the week to reduce the surface temperatures
above the warm water layer. An atmospheric cooling trend
97
is also seen in the records of the 5-day mean temperature
beginning on August 16, 1975 (Figure 89 of Appendix H) .
c. Cross-section J
Figure 84 shows cross-section J comprising Station
5, taken on August 8, 1975 and Stations 31, 32, and 33 taken
on August 18, 1975. At Station 5, the water was warmer than
5°C to a depth of about 16 meters. The remaining Stations,
taken ten days later, show the effects of the surface cooling
which had occurred, leaving a warmer, deep layer of water at
about 15 meters deep.
d. Cross-section K
Figure 8 5 shows cross-section K comprising Sta-
tions 34, 35, 3 6 taken on August 18 and 19, 197 5. This cross-
section approximately marks the eastern boundary of the feature
The water temperature gradually warmed as the distance to
shore decreased. The river water apparently formed a narrow
wedge of warmer, less saline water along the entire length
of the Tuktoyaktuk Peninsula.
In each of the above cross-sections, the density
structure was relatively simple with no indication of the
complex temperature patterns in the water mass.
98
APPENDIX F
SELECTED OCEANOGRAPHIC TIME-SERIES
1. Station 11 , August 15 to 18, 1974
Figure 8 6 shows great variability in the temperature
of the upper 5 meters of the water column over a period of
several days at the same location. Surface temperatures
ranged from 5.09°C to 8.08°C, whereas at 10 meters the tem-
perature was almost constant at -1°C. There was a steep
thermocline between 5 and 10 meters depth throughout the
time series which was typical of most temperature profiles
taken during August, 1974. A result is that the heat content
also changed rapidly with time as the surface layer temperature
changed .
2. Station 48, August 23 to 24, 1975
Figure 8 7 shows the variability of the temperature
versus depth in the water column over a period of several days
at the same location. At the far left in the temperature versus
time plot is a profile taken a week earlier on August 15, 1975
at Station 19 very close to the position of Station 48. During
the following week (August 15-23) there was considerable warm-
ing of the top 10 meters of the water column. Surface tempera-
tures increased from 5.52°C to 7.33°C. At the very end of
the time series, advection of cold water is noticeable as the
temperature contours bend sharply upward, especially between
5 and 10 meters.
99
APPENDIX G
COMPARISON OF SURFACE SALINITIES
Figure 88 shows surface salinities and the polar ice-pack
boundary for the summer of 1974 and the summer of 1975
[Herlinveaux, 1976] . The surface distribution of salinity
indicates that if the pack-ice is offshore, as it was in
1975, low salinity water from the Mackenzie River generally
moves eastward under the influence of the Coriolis effect.
If the pack-ice is unusually close to the shore, as it was
in the summer of 1974, much of the river flow is confined
south of the ice barrier and low-salinity surface water is
seen to accumulate over the Mackenzie Delta.
100
APPENDIX H
SURFACE AIR TEMPERATURES AT BARTER ISLAND AND CAPE PARRY
Barter Island is located about 120 km west of the western-
most edge of the study area. Cape Parry is in Amundsen Gulf
about 200 km east of the easternmost edge of the study area.
Surface air temperatures on a five-day running mean were
available from each of these stations for 1974 and 1975, as
well as mean temperatures based on climatology. These tem-
peratures are plotted in Figure 89.
1. General
Cape Parry is generally 2°C warmer than Barter Island,
indicating the greater prevalence of continental air masses
moving over Cape Parry into the Southeastern Beaufort Sea.
2. Summer of 1974
a. At both locations, the air temperatures were much
colder than normal until mid- July;
b. Both locations had their extreme temperatures
almost simultaneously; and
c. It was warmer at Cape Parry until mid-August
after which it was warmer at Barter Island.
3. Summer of 1975
a. At both locations, air temperatures were much
warmer than normal until mid- July, corresponding to the time
of maximum open-water area;
101
b. The peak temperature of 14 °C at Cape Parry
corresponded to a minimum temperature of 0°C at Barter
Island on August 23, 1975;
c. The September cooling trend was the same at both
locations but the absolute temperatures at Barter Island
were much lower; and
d. With two exceptions, July 19 and August 2, 1975,
this was a consistently warmer summer than 1974.
102
APPENDIX I
EXPLANATION OF MARSDEN SQUARE GRID SYSTEM
1. Marsden Squares
Each Marsden square describes a 10° square of the
earth's surface. The numbering starts at 0°N, 0°W and numbers
the squares westward in a belt moving around the equator.
The numbers increase north and south from the equator. The
Marsden Squares of interest in this study are 230 and 266.
2. Marsden Sub-squares
Each Marsden square is divided into 100 1° sub-squares
which are always oriented so that the lowest number is nearest
the intersection of the Greenwich meridian and the equator.
In Marsden Square 230, the sub-squares of interest are 90-99;
and in Marsden Square 266, the sub-squares of interest are
00-12. The corresponding latitude and longitude can be deter-
mined by knowing the positions of the Marsden Square and the
number of the sub-square. For example, Marsden square 230 is
the 10° square whose lower right corner intersects 60 °N and
130°W. Marsden sub-square 95 then would be the sub-square
whose lower right corner intersects 69 °N and 135 °W. Similarly,
Marsden square 266 is the Marsden square whose lower right
corner intersects 70°N and 130°W. Marsden sub-square 11
refers to that sub-square whose lower right corner intersects
71°N and 131 °W. Note the first digit of the Marsden sub-square
103
refers to the increment in latitude and the second digit
refers to the increment in longitude .
3 . Marsden Sub-sub-squares .
In temperate regions, the Marsden sub-squares are
approximately square. At high latitudes, such as in the
Beaufort Sea, a 1° square becomes rectangular with a height
of 60 nm but a width of only about 20 nm. To preserve the
square appearance of the box, the idea of a Marsden sub-sub-
square is introduced. This makes each square about 4 0 km in
each direction. The number of the Marsden sub-sub-square is
a single digit number indicating the point the lower right
corner of the square intersects the minutes of latitude.
Each Marsden sub-square is divided into three sub-sub-squares
numbered '0', ' 21, '4'. For example, Marsden sub-sub-square
266 110 indicates the square whose lower right corner is
71o0'N and 131o0'W. Similarly, 112 would indicate 71°20'N
and 131°0'W (see Figure 90).
104
Figure 1: The study area in the Southeastern
Beaufort Sea.
105
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Figure 5: Mean Sea Level Atmospheric Pressure Chart "for
May
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Figure 6 : A time sequence showing three stages of the spring
breakup in 1975.
a. There was a large open-water area seaward of
the edge of the landfast ice on 21 Mar 75.
b. The offshore lead increased in width by 2 Apr 7 5
c. Southward advection of the polar pack reduced
the open-water area by 1 May 75.
110
Figure 7: Comparison of open-water area on 13 May 75
and on 16 May 74.
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Figure 8: Comparison of open-water area on 27 May 74
and 02 June 75.
H2
Figure 9: Comparison of open-water area on 19 Jun 74
and 21 Jun 75.
113
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OF OCEAN
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m
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Figure 13. Typical Summer Fluxes in the SE Beaufort Sea
(SIGN IS INDICATED IN BRACKETS)
Q* (-
Qe (+
Qh (+
Qa (-
Qt (-
Qw (+
Qf (+
Qi (+
Qs (+
THE NET RADIATION DOWN
THE HEAT LOSS DUE TO EVAPORATION
THE UPWARD TRANSFER OF SENSIBLE HEAT
THE RESULTANT DOWNWARD ATMOSPHERIC FLUX
THE INPUT OF THE MACKENZIE RIVER
THE HEAT USED TO WARM THE TOP LAYER
THE HEAT USED TO MELT ICE-IN-PLACE
THE HEAT USED TO MELT IMPORTED ICE
THE STORAGE CHANGE
117
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INCIDENT SOLAR RADIATION
SACHS HARBOR
INUVIK
* a . CALCULATED
AUGUST 1974
— 'O
JO
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CD.
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1.00
7.00 • 13.00 19.00 25.00
TIME (DAY OF MONTH)
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AUGUST 1975
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TIME (DAT OF MONTH)
Ti.oo
Figure 16
120
0
- 100
-200
Ki
-400
-500
SUMMARY OF ATMOSPHERIC FLUXES (Ly/DAY)
MAY JUN JUL AUG SEP
1 1 1 1 1
-A- 1974
-O- 1975
-6Q0 L. A. 'ncident Solar Radiation at Sachs Harbor
- 100
Q*
-300
-400
\
\
o
L B. Net Radiation
standard
deviation
Q
100r
fo"TV C^Q'Q^'A
C. Latent Heat Flux
Q
100 r
H
D. Sensible Heat Flux
Figure 17
121
ATMOSPHERIC FLUX QA (Ly/DAY)
300
200
100 -
co
CO
O
5
LU
X
-100
-200
Standard
Deviation
ONSHORE
WINDS
-300
ONSHORE
WINDS
OFFSHORE
WINDS
MAY
JUN
JUL
AUG
Figure 18
122
ACCUMULATED HEAT CONTENT Q
A
CO
a 1974 — £r— 6-
0 .
^^ \ 1975 -0--0--
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MAY JUNE JULY AUG
Figure 19
123
COMPARISON OF ATMOSPHERIC FLUXES QA (Ly/DAY)
100
0
-100
-200
-300
-400
1974 - SE BEAUFORT SEA
O — 1975 - SE BEAUFORT SEA
-• 1962 - BARROW STRAIT (Huyer 8 Barber)
1919-1942 BAFFIN BAY ( Walmsley )
<
<
LU
X
%
V
L
+
+
+
MAY JUNE JULY AUG
Figure 20
124
SUMMARY OF OCEANIC FLUXES (LY/DAY)
MAY JUN JUL AUG SEP
-200
QT h
-400 -
-600 -
A. RIVER HEAT
100 r
- 100
warming
cooling R
+
1 O^-l
WARMING
/
9
400
200
-200
-400
9
Ice Coverage
Decreases
Ice Coverage
Increases
C. MELTING
200
Qi o
-200
Ice Import
h
- Ice Export
-A- 1974
-GH975
D. ICE ADVECTION
Figure 21
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Landfasi Ice. MacKenzie Bay
RIVER WATER TEMPERATURE (°C)
Jul Aug S*ot Oct Now Dec ' Ian Feo Mar Apr May Jun
1974 197S
40.000 -
■o
C
O
i
2 30.000-
MACKENZIE RIVER DISCHARGE
■ » I
1 I I
Jul Aug S«« Oct Nov Dec ! Jan Teb Mar Apr May Jun
1974 1975
Figure 23: Mackenzie River discharge volume and temperature
and the relationship to breakup and freeze-up
of landfast ice in Mackenzie Bay.
127
128
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129
HEAT DUE TO ICE MELTING IN STUDY AREA
vs. OBSERVED ICE CONCENTRATION
9
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Figure 26
130
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131
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AUGUST 1974
S
si-
3
35
1*
O
UJO
WIND SPEED
»'.oo
7*. 00 10-00 13.00 18.00 19.00
TIME (DAT OF MONTH)
Ti.00
.00
22.00
23.00
28.00
RUGUST 1974
WIND DIRECTION
3
i
♦
♦
♦
♦
♦
3
o
sSL
« ♦
°iToo
4.00
7.00
10.00 13.00 18.00 19.00
TIME CQflY OF MONTH)
22.00
29.00
28.00
91.00
Figure 28 : Wind speeds and wind direction versus time
during August 1974 from marine observations
132
27
28,
r
5s
AUGUST 19714
RIR TEMPERATURE
UJ
1.00
*-00
7.00
10.00
13.00
TIME
18.00 18.00
CORT OF MONTH)
.00
23. 00
28.00
SI. 00
3
UJ
u
28
oils'
c
o
UJ
t
UJ
AUGUST 1974
WATER TEMPERATURE
(DEGREES CELSIUS)
1.00
I. 00
7.00
lb.oo
19.00 18.00 19.00
TIME (DAT OF MONTH)
22.00
29.00
28.00
91.00
Figure 29 :
Air temperatures and water temperatures versus
time during August 1974 from marine observations
133
I AUGUST 1974
en
=3
_»
ui
u
o
±1
a
DEW POINT TEMPERATURE
(DEGREES CELSIUS)
V
A^^.
2§
a
8
i
».oo
l. 00
7. 00
10.00
13.00 18. 00 19.00
TIME (DAT OF MONTH)
22.00
25.00
28.00
31.00
AUGUST 1974
CLOUD AMOUNT (TENTHS)
^.00
n.oo
7.00
10.00
13.00 18.00 19.00
TIME (DAT OF MONTH)
22.00
29.00
28.00
91.00
Figure 30
Dew point temperatures and cloud amounts versus
time during August 1974 from marine observations
134
AUGUST 1975
I ' WIND SPEED
^.00 »!aO 7.00 lb. 00 13.00 18.00 li.00 22.00 SToO 28.00 31.00
TIME (ORT OF MONTH)
8
e
8
A
«*1
o
5
is
AUGUST 1975
WIND DIRECTION
♦
♦ ♦
♦ ♦
• ♦ •
♦ ♦ • ♦ ♦ ♦
•
♦ ♦
• ♦
•♦ ♦♦
♦
♦
• «♦
♦
♦ •
■kTro
«.oo
7.00
13. C
10.00 13.00 18.00 19.00
TIME (ORT OF MONTH)
22.00
IT.
00
28.00
■♦— »
31.00
Figure 31: Winds speeds and wind direction versus time
during August 1975 from marine observations
13 5
AUGUST 1975
AIR TEMPERATURE t
To7
7'. oo 10.00 is.oo it.ao 19.00
TIME COAT OF M0NTH1
'1T0F
.00
.00
28.00
31.00
-J
UJ
o
S8|
Um"4
cc
o
AUGUST 1975
WATER TEMPERATURE!
(DEGREES CELSIUS!
'l.OO
».00
7.00
10.00 13.00 16.00 19.00 22.00
TIME (DAT OF MONTH)
23.00
28.00
31.00
Figure 32: Air temperatures and water temperatures versus time
during August 1975 from marine observations.
13 6
I AUGUST 1975
S
DEW POINT TEMPERATURE
(DEGREES CELSIUS)
i'.oo
SToo 37
.00
7.00
lb. 00
13.00 18.00 19.00
TIME (DAT OF MONTH)
00
28.00
St. 00
AUGUST 1975
CLOUD AMOUNT (TENTHS)
8
h
Z
28
^.00
13.00 18.00 19.00
TIME (DAT OF MONTH)
22.00
28.00
31.00
Figure 33 : Dew point temperatures and cloud amounts versus
time during August 1974 from marine observations
137
AUGUST 1974
a
SO
3*
Ui
a.
£8
o
§■
3
Is
Ui
SENSIBLE HEAT FLUX
OVER WATER ONLY
w
4.00
lb. oo
TIME
"5:
"a:
l. 00
7.00
10.00
10.00 19.00
(OAT OF MONTH)
oo
oo
29.00
31.00
3
■
Si
AUGUST 1974
SENSIBLE HEAT FLUX
OVER ENTIRE AREA
0»
So
3*
Ui
a.
S3
up
58
a.
58
1.00
4.00
7.00
10.00
13.00 19.00 19.00
TIME (DAT OF MONTH)
22.00
2S.00
28.00
31.00
Figure 34: Sensible heat flux versus time in August 1974.
138
AUGUST 19714
Si
LATENT HEAT FLUX
OVER WATER ONLY
UJ
528]
o
2^
UJ
X
3
•i.oo
%.oo
7.00
10.00
13.00 16.00 19.00
TIME (OflT OF MONTH)
22.00
29.00
28.00
31.00
3
8-
AUGUST 1974
LATENT HEAT
OVER ENTIRE
FLUX
AREA
CO
°»
c
UJ
a.
a-
is
58
Ui
22.00 25.00
Latent heat flux versus time in August 1974
1.00
4.00
7.00
10.00
13.00 18.00 19.00
TIME (OflT OF MONTH)
28.00
31.00
Figure 35:
139
AUGUST 19714
LATENT. HEAT FLUX
OVER ICE ONLY
oS
>•©
SO
UJ
281
T
*£=,
5?
't.oo
1.00
7.00
10. 00
13.00
TIME
IS. 00 19.00
(DAY OF MONTH]
.00
23.00
28. 00
31.00
AUGUST 1974
SENSIBLE HEAT FLUX
OVER ICE ONLY
't.oo
4.00
7.00
10.00
Figure 36
13.00 10.00 19.00
TIME (DAT OF MONTHJ
sensible heat
22.00
25.00
20.00
31.00
Latent and
time .in August 1974.
fluxes over ice versus
140
Sn
AUGUST 1974
o
X
-3
z •
S3
NET RADIATION Q*
OVER WATER ONLY
i
4.00
10.00
l5T0O 18.00 19.00
TIME (OBT OF MQNTHJ
.00
7.00
22.00
25.00
28.00
31.00
BASED ON CflLCULRTED RflDIflTIQN FLUX
e
Si
AUGUST 1974
en
-8
S3
NET RADIATION Q*
OVER ENTIRE RRER
'1.00
■4.00
7.00
22.00 23.00
28.00
Tt.00
F.igure 37
10.00 13.00 18.00 18.00
TIME (DAT OF MONTH) _ , QnA
Net radiation flux versus time in August 1974
141
AUGUST 1974
Y.oo
ATMOSPHERIC FLUX Qa
OVER WATER ONLY
•i.OO
7.00
10.00 13-00 18.00 13.00 32.00
TIME (DRY OF MONTHJ
25.00 29.00 31.00
is
ts
Ujrf
u
ft
3
a.
53
s
UJ
X
BASED ON CALCULATED RADIATION FLUX
AUGUST 1974
1.00
ATMOSPHERIC FLUX Qa
OVER ENTIRE RRER
T
i.oo
7.00
10.00 13.00 18.00 19.00 22.00
TIME (DRY OF MONTH)
25.00 29.00 31.00
Figure 38: Atmospheric flux versus time in August 1974.
142
HEAT FLUXES VERSUS WIND DIRECTION
AUGUST 1974
SENSIBLE HEAT
NW \
0.00
50.00
NET RADIATION
□
□ i
a
inn
I
m
a
p
-£o7
00
0.00
xlO1
iO.'OO
LATENT HEAT
NW \
SW /
SE\
NE
/
JSp ana
b
i
a a
\
-50.00 0.00
0.00
ATMOSPHERIC FLUX
jpu Da
33 I'l'i'i
a a anr a^
a
a an
Dflja
a
&
a
-50.00 0.00
Kip1 , k 1 0
HEAT FLUX (LANGLETS PER OAT)
Figure 39
143
.0.00
AUGUST 1975
SENSIBLE HEAT FLUX
OVER WATER ONLY
'i.oo «'.oo 7735 lb. oo lb. oo lb. oo iCToo Sim 37oo 20.00 31.00
TIME COBT OF MONTH!
3l
x9
oca
£8
58
AUGUST 1375
SENSIBLE HEAT FLUX
OVER ENTIRE AREA
^A^/— ks^AV^^
LOO 1.00 7.00 10.00 13.00 18.00 19.00 22.00 iSToO 28.00 31.00
TIME (DRY OF MONTH)
Figure
40: Sensible heat flux versus time in August 1975
144
AUGUST 1975
LATENT HEAT FLUX
OVER WATER ONLT
13.00 ls.ao isloo STaa
TIME (DRY OF MONTH)
3!
aa
sk.aa
31.00
AUGUST 197S
LATENT HEAT FLUX
OVER ENTIRE AREA
Wfr** ^)
loo
1.00
7.00
10.00 13.00 IS. 00 19.00
TIME (DAT OF MONTH)
22.00
.00
28.00
31.00
Figure 41: Latent heat flux versus time in August 1975
145
AUGUST 1975
LATENT HEAT FLUX
OYER ICE ONLY
.90 1.00 7.00
10.00 13-00 10.00 19.00 22.00 SToO
TIME (ORT OF MONTH)
31.00
AUGUST 1975
SENSIBLE HEAT FLUX
OVER ICE ONLY
TT*W m*y*w*
19.00 18.00 19.00 22.00
TIME (DAT OF MONTHJ
29.00
28.00
91.00
Figure 42:
Latent and sensible heat fluxes over the ice versus
time in August 1975.
146
a
AUGUST 1975
NET RAOIATION Q*
OVER WATER ONLY
10.00 13.00 IS. 00 19.00
TIME (DRY OF MONTH)
22.00 25.00 28.00 31.00
BRSED ON CALCULATED RADIATION FLUX
AUGUST 1975
NET RflDIflTION Q'
OVER ENTIRE AREA
4.00
10.00 13.00 18.00 19.00 22.00
TIME (OflT OF MONTH)
28.00 31.00
Figure 43: Net radiation flux versus time in August 1975
147
AUGUST 1975
ATMOSPHERIC FLUX Qa
OVER WATER ONLY
1. 00 14.00
7.00
10.00
13.00 16.00 19.00
TIME CORY OF MONTH)
32.00 25.00 29.00 31.00
BASED ON CALCULATED RADIATION FLUX
AUGUST 1975
ATMOSPHERIC FLUX Qa
OVER ENTIRE AREA
1.00 <t. 00
7.00
10.00 13.00 16.00 19.00 22.00 25.00 26.00 31.00
TIME CDRT OF MONTH)
Figure 44: Atmospheric flux versus time in August 1975.
148
HEAT FLUXES VERSUS WIND DIRECTION
AUGUST 1975
SENSIBLE HEA1
NH \
SH /
SE\
NE
-50.00
0.00
xlO1
50.00
NET RADIATION
-50.00
0.00
xlO1
50.00
LATENT HEAT
iWi Q
NN \
□1
I^FcP
SW /•
□ c
ted ce a
□
3
SE\
mm
IMjJ
La
fern
NE
/
-50.00 0.00
*1
8:
ATMOSPHERIC FLUX
□ _ CDGJ □ GE
□ m
-50.00 0.00
xlO1
50.00
HEAT FLOX (LANGLETS PER DAY)
Figure 45
149
50.00
DRILY AVERAGE atmospheric flux qa
a
o
a
_ o
«— 'CM
X
OcJ'
o
xa
a
o
o
a*.
AUGUST 1974
IDVER ENTIRE AREA
.OVER NATER ONLY
t.oo
6'.00
11 .00
16.00
21.00
26.00
Tl.00
AUGUST 1975
1.00
6.00 11.00 16.00 21.00
TIME (DAT OF MONTH)
26.00
31.00
Figure 4 6
150
RCCUMULR ED atmospheric heat qa
•?-
cvj
*§4
flUGUST 1974
IDVER ENTIRE ARE
.OVER WATER 0
'i.oo
6.00
tt.00
16.00
21.00
26.00
31.00
AUGUST 1975
1.00
6.00
11.00 16.00 21.00
TIME (DAT OF MONTH)
26.00
31.00
Figure 47
151
152
153
154
155
-1 I
156
157
WEST OR NORTHWEST WINOS
EAST OR SOUTHEAST WINOS
Figure 54 Onshore and offshore movement ol Mackenzie River wuto
clue to wind.
158
159
160
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SAUNITY 0/00, OENSITY <rT
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Figure 72:
1975 STATION 13
Salinity, density, and tempera ture versus depth
at Station 12, August 18, 1974 and at
Station 13, August 14, 1975.
176
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TEMPERATURE CROSS-SECTION 1974
24
DENSITY CROSS-SECTION 1974
2T
28
Figure 74: Temperature and density cross-section A.
178
TEMPERATURE CROSS-SECTION 1974
DENSITY CROSS SECTION 1974
Figure 75:
Temperature and density cross section B. A
cold water intrusion is outlined by the -1.5°C
isotherm.
179
TEMPERATURE CROSS-SECTION 1974
DENSITY CROSS-SECTION 1974
Figure 76:
Temperature and density cross-section C. Shown
are two tongues of warm water at the surface and
a cold intrusion riding up the continental shelf
180
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TEMPERATURE CROSS-SECTION 1975
DENSITY CROSS-SECTION 1975
Figure 78:
Temperature and density cross-section D. A wedge of
warm water at the surface decreases in depth with the
distance seaward, and cold water is seen along the
continental slope at a depth of about 25 meters.
182
43
TEMPERATURE CROSS-SECTION 1975
42
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OENSITY CROSS-SECTION 1975
Figure 79
Temperature and density cross-section E. A wedge
of warm water decreases in thickness with the
distance seaward.
183
TEMPERATURE CROSS-SECTION 1973
12
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DENSITY CROSS SECTION 1975
Figure 80:
Temperature and density cross-section F. An
intrusion of cold water rises inshore to a
depth of 15 meters along the continental slope
184
TEMPERATURE CROSS-SECTION 1975
DENSITY CROSS-SECTION 1975
Figure 81:
Temperature and density cross-section G. An
intrusion of cold water is seen along the con-
tinental slope to a depth of about 18 meters. Also
shown is an upwelling of cold water north of Richard ' s
Island indicated by the decreasing water surface
temperatures between Station 39 and the shore.
185
TEMPERATURE
DENSITY
Figure 82:
Temperature and density cross-section H. There
was a warm wedge which thinned as the distance
seaward increased.
186
27
DENSITY
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Figure 83: Temperature and density cross-section I. There was
a well-mixed layer of 5°C water to a depth of 15
meters between Station 27 and 29 and a core of
warmer 3°C water at 20 meters below Station 27.
187
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188
TEMPERATURE
CROSS-SECTION 1973
6 33
34
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m 1
[BOTTOM
10
15 g
X
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25
30
DENSITY CROSS-SECTION 1975
Figure 85.
Temperature and density cross-section K. There
was a relatively simple temperature structure with
a decreasing thickness of a warm wedge as the
distance seaward increased.
189
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190
AUGUST
15 23
S'qtlgn 19
DATE
TIME SERIES OF STATIONS 19,48 AT APPROXIMATELY THE SAME POSITION
15-24 AUGUST 1375
(HOURLY MEASUREMENTS ON 23,24 AUGUST)
SALINITY %•
Figure 87: Hourly time series taken at Stations 19 and 48,
north of Tuktoyaktuk, August 23-24, 1975.
191
in
192
10
SURFACE TEMPERATURES FROM ICE CHARTS
5 DAY MEAN
BARTER ISLAND
-5
JUNE
20 28
U
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-5
LEGEND
1974
NORMAL
— 1975
«^v
JULY
05 12 19
AUG
09 16
CAPE PARRY
UUNE JULY
20 28 03 12
AUG
19 26 02^ 09
Figure 89:
Comparison of surface air temperatures at Barter
Island and Cape Parry based on 5-day mean tem-
peratures in 1974 and 1975 from June 20 to
October 10 of each year.
193
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194
LIST OF REFERENCES
Badgely, F.I., Heat Budget of the Surface of the Arctic Ocean ,
Proceedings of the Symposium on the Arctic Heat Budget
and Atmospheric Circulation 31 Jan-4 Feb 1966, National'
Science Foundation Memorandum RM-5233-NSF December 1966,
pp 269-277.
Burns, B.M., The Climate of the Mackenzie Valley - Beaufort
Sea, Information Canada, Ottawa, Volume 1, 1973, Volume
2, 1974.
Davies, K.F., Mackenzie River Input to the Beaufort Sea,
Beaufort Sea Technical Report #15, Department of the
Environment, Victoria, BC, December, 1975.
Fraker, M.A., Gordon, CD., McDonald, J.W., Ford, J.K., and
Cambers, G., White Whale Distribution and Abundance and
the Relationship to Physical and Chemical Character is tics
of the Mackenzie Estuary, Fisheries and Marine Science
Technical Report No. 8 63, Department of Fisheries and
the Environment, Winnipeg, Dec 1979.
Gresswell, R. , and Huxley, A., Standard Encyclopedia of the
World's Rivers and Lakes, G.P. Putnam and Sons, New
York, 1965.
Herlinveaux, R.H., de Lange Boom, B.R., Wilton, G.R., Salinity,
Temperature, Turbidity and Meteorological Observations in
the Beaufort Sea: Summer 1974, Spring and Summer 1975,
Unpublished Manuscript, Institute of Ocean Sciences,
Patricia Bay, Victoria, B.C., December, 1976.
Huyer, A., and Barber, F.G., A Heat Budget of the Water in
Barrow Strait for 1962, Manuscript Report Series No. 12,
Marine Sciences Branch, Department of Energy, Mines and
Resources, The Queen's Printer for Canada, Ottawa, 1970.
Langleben, M.P., Albedo of Ice-Infested Waters in the Channels
of the Canadian Archipelago, pp. 134-142, Energy Fluxes
over Polar Surfaces, Proceedings of the IAMAP/IAPSO/SCAR/
WMO Symposium, Moscow, 3-5 August 1971, Technical Note
No. 129, World Meteorological Organization, Geneva,
Switzerland, 1973.
Laevastu , T., Factors Affecting the Temperature of the Surface
Layer of the Sea, Merentut kimuslaitoksen Julkaisu
Havsforskningsinstitutets Skrift, No 195, Helsinki, 1960.
195
MacNeill, M.R., and Garrett, J.F., Open Water Surface Currents,
Beaufort Sea Technical Report #17, Department of the
Environment, Victoria, B.C., December, 1975.
Markham, W.E., Ice Climatology of the Beaufort Sea, Beaufort
Sea Technical Report #26, Department of the Environment,
Victoria, B.C., December, 1975.
Matheson, K.M., The Meteorological Effect on Ice in the Gulf
of St. Lawrence, Manuscript Report No. 3, Marine Sciences
Center, McGill University Montreal, September, 1967.
Maykut, G.A., and Grenfell, T.C., The Spectral Distribution
of Light Beneath First- Year Sea-Ice in the Arctic Ocean,
pp. 554-563, Limnology and Oceanography 20, 4, 1975.
Milne, A.R., Personal Communication.
O'Neill, A.D.J. , and Gray, D.M., Solar Radiation Penetration
Through Snow, pp. 227-241, I Proceedings of the Banff
Symposium, September, 197 2, on the Role of Snow and Ice
in Hydrology, IAHS Publication 107, Volume 1, UNESCO/
WMO/IAHS, 1972.
Orvig, S., Climates of the Polar Regions, World Survey of
Climatology, Volume 14, p370, 1970.
Sellers, W.D., Physical Climatology, p272, U. of Chicago Press
Chicago, 1965 (Quoted in Walker, 1975) .
Shuleikin, V.V., Molecular Physics of the Sea, Physics of
the Sea Part VIII, pp727-786, 1953 (USHO Translation,
Washington, 1957) (Quoted in Walmsley, 1966) .
Sverdrup, H.U., Johnson, M.W., Fleming, R.H., The Oceans,
Their Physics, Chemistry and General Biology, Prentice
Hall, Inc., Englewood Cliffs, N.J., 1942.
Swinbank, W.C., Evaporation from the Oceans, Scientific
Report No. 12, A.F.C.R.C., TN-60-211 [Quoted in Walmsley,
1966) .
Untersteiner, N. , On the Mass and Heat Budget of Arctic Sea
Ice, Arch. Meteor. Geophys . Biokl. Series A, Bd. 12, pp
151-182, Vienna, 1961.
Vowinckel, E., and Taylor, B., Energy Balance of the Arctic :
Evaporation and Sensible Heat Flux over the Arctic Ocean,
Arch. Meteor. Geophys. Biokl. Serie B.
Walmsley, J.L., Ice Cover and Surface Heat Fluxes in Baffin
Bay, Manuscript Report No. 2, Marine Sciences Center,
McGill University, Montreal, October, 1966.
196
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Thesis 19070;
T933 Tummers
c.l Heat budgets of the
Southeast Beafort Sea
for the years 1974 and
1975.
4 *i»#tu 2 7 205
Thesis 1 9 0
T933 Tummers
c.l Heat budgets of the
Southeast Beafort Sea
for the years 1974 and
1975.
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9/11